Consider the following statements: Automatic signalling system results in 1. greater risk 2. higher efficiency 3. avoidance of block instruments 4. higher operating cost Of these statements A. I and 2 are correct B. 3 and 4 are correct C. 1 and 4 are correct D. 2 and 3 are correct

Here is a brief explanation of each statement:

1. Greater risk: Automatic signalling systems can lead to greater risk if they are not properly maintained or if there is a problem with the system. This is because they are designed to operate without human intervention, so if there is a problem, it can go unnoticed for some time.
2. Higher efficiency: Automatic signalling systems can lead to higher efficiency because they can control the movement of trains more precisely than humans can. This can help to reduce delays and improve the flow of traffic.
3. Avoidance of block instruments: Automatic signalling systems can avoid the need for block instruments, which are devices that are used to control the movement of trains in a section of track. This can save money and improve efficiency.
4. Higher operating cost: Automatic signalling systems can have higher operating costs than traditional signalling systems. This is because they require more complex infrastructure and regular maintenance.

I hope this helps!