Answer:
Crosstalk, Jitter, Impulse noise.
Explanation:
Crosstalk is a network error that occurs when one pair of cable causes interference on another pair of cables thereby preventing efficient data transmission.
Jitter may also impair the accuracy of the data being transmitted across network because minute variations in amplitude, phase, and frequency always occur. The generation of a perfect carrier signal in an analog circuit is almost impossible. The signal may be affected by continuous and rapid network gains or phase changes. 
Impulse noise (also referred to as spikes) is the primary source of errors in data communications.  Impulse noise can be caused by positioning a communications cable near a source of intermittent but strong electromagnetic pulses, such as an elevator motor.
Counter measures
Shielding (protecting wires by covering them with an insulating coating) is one of the best ways to prevent impulse noise, cross-talk.
Amplifiers can be used to increase signal strength since the connection would run across 4 floors.
 
        
             
        
        
        
Answer: (A) Computer networks allow individuals to share many types of resources.  
Explanation:
  Computer network is basically known as digital telecommunication that allowing various nodes to sharing different types of resources in the network. In the computer network, the data link is establish over the cable like wire and optic media in the network. 
 The network basically allow sharing of the computing network and various types of resources in the networking. 
It can allow sharing resources like printers, exchange files and CDs. There are mainly two types of networking that are: LAN and WAN.