Select the most appropriate option to substitute the highlighted segment in the given sentence to make it a meaningful sentence. If no substitution is required, select ‘No substitution’.
One must not only have the ability to read voraciously but have the necessary training in comprehending and remembering all the relevant details.

Correct option is D

The correct substitution of the highlighted words is (d) not only have the ability to read voraciously but also have.
Explanation:
This is a case of correlative conjunctions – not only... but also – and they must be grammatically parallel. The first part has “have the ability to read”, so the second clause must also start with “have” to maintain parallelism.
Incorrect:
· “…but have the necessary training…” → breaks parallelism
· Correct:
· “…but also have the necessary training…”
Grammatical Rule Used:
Correlative Conjunction Rule: not only... but also must join grammatically similar structures.
Example:
· He not only sings beautifully but also dances gracefully.
· She not only has money but also has influence.