Which word denotes 'a duty or an activity that one must perform'?

• A. A formal event
• B. A base on which something is built
• C. Function
• D. A purpose

Answer: (C)

The concept being tested is understanding function as the role or duty someone has to perform. When we talk about a person’s function, we’re referring to the activity or responsibility that is expected of them in a given role. For example, a teacher’s function might be to educate and guide students—the duties they are responsible for in that position. That sense aligns with “a duty or an activity one must perform,” which is exactly what the item is asking for.

Note that function can also mean a formal event or the purpose of something, but those are different senses. A formal event is a social gathering, not the obligation tied to a role; a base or foundation and a purpose are related ideas but do not capture the performative duty aspect as directly. So, the best fit for a duty or activity one must perform is function.