Select the option that can be used as a one-word substitute for the given group of words or phrase.
An extra profit or allowance additional to a main income etc.

Correct option is C

The correct one-word substitute for "an extra profit or allowance additional to a main income" is (c) perquisite.
• Perquisite: refers to a benefit or privilege enjoyed as a result of one's position or job, often in addition to one's regular salary or wages.
• Perquisite: अतिरिक्त लाभ (Hindi meaning).
• Example: One of the perquisites of being a manager is having access to a company car.
Meanings of the given other options:
• (a) Perplexity: A state of confusion or uncertainty.
• (b) Persecute: To subject someone to hostility and ill-treatment, especially because of their race, political or religious beliefs.
• (d) Persevere: To continue in a course of action even in the face of difficulty or with little or no prospect of success.