Select the most appropriate option to substitute the highlighted segment in the given sentence. If there is no need to substitute it, select ‘No improvement’.
If you want to grow, you must apply in whatever you do.

Correct option is B

The correct substitution of the highlighted words is (b) must apply yourself to.
Explanation: The correct structure requires a reflexive verb followed by a prepositional phrase. "Apply yourself to something" means to put effort into it.
Grammatical rule used:
When using “apply” in the context of making effort, it is a reflexive verb and must be followed by “to” and the activity.
Example: You must apply yourself to your studies to succeed.
Why other options are incorrect:
· (a) should applied in: Wrong tense and incorrect preposition ("should apply" is correct, and "in" is wrong usage)
· (c) No improvement: Incorrect as “apply in” is not idiomatically or grammatically correct in this context
· (d) ought to apply yourselves in: Incorrect pronoun "yourselves" (subject is singular) and incorrect preposition "in"