to hit below the belt : to be unfair/cruel (attack)
● The boxer hit the contender below the belt and the crowd began to behave furiously. The best option is to attack unfairly.

Correct Option: D

to hit below the belt : to be unfair/cruel (attack)
● The boxer hit the contender below the belt and the crowd began to behave furiously. The best option is to attack unfairly.

all at sea : confused and not knowing what to do
● I’m all at sea with these new rules and regulations. The best option is puzzled.

Correct Option: C

all at sea : confused and not knowing what to do
● I’m all at sea with these new rules and regulations. The best option is puzzled.

sought after : wanted by many people, because it is of very good quality or difficult to get or to find
● He was much sought after as a throat specialist, particularly by singers. The best option is in great demand.

Correct Option: C

sought after : wanted by many people, because it is of very good quality or difficult to get or to find
● He was much sought after as a throat specialist, particularly by singers. The best option is in great demand.

build castles in the air : plans or dreams that are not likely to happen or come true
● I really like to sit on the porch in the evening, building castles in the air. The best option is daydream.

Correct Option: B

build castles in the air : plans or dreams that are not likely to happen or come true
● I really like to sit on the porch in the evening, building castles in the air. The best option is daydream.

by fits and starts : impulsively and irregularly
● A sincere student works regularly, not by fits and starts The best option is irregularly.

Correct Option: B

by fits and starts : impulsively and irregularly
● A sincere student works regularly, not by fits and starts The best option is irregularly.