Stress can _____ your ability to concentrate.

• A. affect
• B. effect
• C. influence
• D. hinder

Answer: (A)

This question is about choosing the right verb to describe how something changes another thing. Stress can affect your ability to concentrate. Here, affect is the natural, everyday verb meaning to influence or produce a change in something.

Effect is a noun, not a verb, so it wouldn’t fit the sentence structure (you can say stress can have an effect on your ability to concentrate, but not stress can effect...). Influence is grammatically correct and close in meaning, but affect is the more common, concise choice for talking about how stress changes concentration in a general sense. Hinder would work too, but it implies actively blocking or delaying concentration in a more specific way, which isn’t the nuance intended here. So the best fit is affect.