Which type of staff officer's role is to monitor, assess and coordinate current operations, conduct short-range and mid-range planning and coodinate training in Military?

The fact that the word operations has been mentioned, it already means that this refers to G3. This means that the answer to this question is letter B. G3 is in charge of anything that has to do with operations. G1 is in charge of personnel, G2 is in charge of intelligence, G4 is in charge of logistics, and G5 is in charge of civil-military operations.

The different staff officers usually have different things to work on depending on what has been assigned to them but there are still times when they have to work together to ensure that all of the things that they have planned will go on smoothly.