Select the most appropriate option to substitute the highlighted segment in the given
sentence. If there is no need to substitute it, select ‘No substitution’.
It is time we should have done something useful.

Correct option is D

The correct substitution of the highlighted words is (d) did.
The correct grammatical structure for expressing a necessary action in the past is 'It is time we did something useful.'
In this context, using "did" is a more concise and appropriate way to convey the intended meaning, indicating that it's time to take action without the need for additional auxiliary verbs.