Select the option that will improve the highlighted part of the sentence. In case no improvement is needed, select ‘No improvement required’.
Antibiotics are one off the most commonly prescribed drugs in the world.

Correct option is C

The correct substitution of the highlighted words is (c) are one of the.
Explanation: The phrase “one off” is incorrect.
The correct expression is “one of the” when referring to a particular item from a group. Also, since “antibiotics” is plural, the verb "are" is correct.
The noun phrase following "one of the" should always be plural.
Grammatical rule used:
· “One of the + plural noun” is the correct grammatical structure.
· Subject-verb agreement must be maintained.
· "Off" is a preposition of separation and not used in this context; "of" is the correct preposition of inclusion.
Example:
❌ He is one off the best players.
✅ He is one of the best players.