Spell the word meaning 'required'.

• A. Obligatory
• B. Compulsory
• C. Mandatory
• D. Required

Answer: (C)

The main idea here is choosing a word that conveys a clear obligation imposed by rule or authority. The best fit is the word that is most commonly used to describe something you must do because of a rule, policy, or law. That word is a straightforward synonym for “required” in formal contexts and signals an official obligation: you must comply.

While other options are close in meaning, they carry slightly different nuances. One such word also means you ought to do it, but it can feel more like a moral or social expectation. Another is often used in legal or formal settings and emphasizes enforcement, but it isn’t as universally used to denote a rule-driven requirement in everyday language. The remaining option literally means “needed” or “necessary,” but it doesn’t capture the sense of obligation that comes from an authoritative directive as well as the best fit does.

So, the word that best expresses something you must do because of an external rule or directive is the one commonly used to denote official obligation: mandatory.