Some of the different networks based on size are:

• Personal Area Network, or PAN
• Local Area Network, or LAN
• Metropolitan Area Network, or MAN
• Wide Area Network, or WAN

1. Personal Area Network (PAN)

The smallest and must basic type of network, A PAN is made up of a wireless modem, a computer or two phones, printers, tablets, etc, and revolves around one person in one building. These types of networks are typically found in small offices or homes, and are managed by ore person or organisation from a single device.

2. Local Area Network (LAN)

LANS connect groups of computers and low-voltage devices together across short distances (within a building or between a group of two or three buildings in close proximity to each other) to share information and resources. Enterprises typically manage and maintain LANS. Using routers, LANS can  connect to wide area networks (WANS, explained below) to rapidly and safely transfer data.

3. Metropolitan Area Network (MAN)

These types of networks are larger than LANS but smaller than WANS - and incorporate elements from both types of networks. MANS span an entire geographic area (typically a town or city, but sometimes a campus). Ownership and maintenance is handled by either a single person or company.

4.Wide Area Network (WAN)

Slightly more complex than a LAN, a WAN connects computers together across longer physical distances. This allows computers and low-voltage devices to be remotely connected to each other over one large network to communicate even when they're miles apart. The Internet is the mast basic example of a WAN, connecting all computers together around the world. Because of WAN's vast reach, it is typically owned and maintained by multiple administrators or the public.

In terms of  purpose, many networks can be considered general purpose networks; it means they are used everything from sending files to a printer to accessing the Internet. Some types of networks, however, serve a very particular purpose.

In the question:

Which of the following refers to all small, single - site network ?

The answer is PAN.

Hence the option A is correct.

Network and It's Types

It is a collection of two or more computers, which are connected together to share information and resources.Computer network is a combination of hardware and software that allows communication between computers over a network.

Types of Networks

There are different types of computer networks. Computer networks can be characterised by their size as well as their purpose. The size of a network can be expressed by the geographic area they occupy and the number of computers that are part of the network. Networks can cover anything from a handful of devices within a single room to millions of devices spread across the entire globe.

Some of the different networks based on size are:

• Personal Area Network, or PAN
• Local Area Network, or LAN
• Metropolitan Area Network, or MAN
• Wide Area Network, or WAN

In the question:

A Combination of hardware and software that allows communication and electronic transfer of information between computers is a  _______     

The answer is Network.

Hence the option A is correct.              

Local Area Network (LAN)

LANS connect groups of computers and low-voltage devices together across short distances (within a building or between a group of two or three buildings in close proximity to each other) to share information and resources. Enterprises typically manage and maintain LANS. Using routers, LANS can connect to wide area networks (WANS, explained below) to rapidly and safely transfer data. 

Local area networks, which enable multiple devices to communicate and share data, are also created and maintained by routers. LANs can exist even when Internet access is not readily available. As opposed to LANs, modems are unable to establish direct connections with numerous devices.

• A local area network (LAN) is a collection of computers and related devices that connects to a server over a shared wired or wireless network. Modem items is not used in Local Area Networks (LAN).

In the Question:

Which network connect groups of computers and low-voltage devices together across short distances?

The answer is LAN.

Hence the option A is correct.