Question

obligatory; mandatory; subject to command or order (adj.)
imperative
unwonted
apathetic
intangible

Explanation:

We need to find the word that matches the definition "Obligatory; mandatory; subject to command or order (adj.)". Let's analyze each option:

• "Imperative" means of vital importance or crucial, and also has the meaning of being mandatory or obligatory (as an adjective), which matches the given definition.
• "Unwonted" means not customary or usual, so it doesn't match.
• "Apathetic" means showing no interest or concern, so it doesn't match.
• "Intangible" means not able to be touched or grasped, so it doesn't match.

Answer:

A. Imperative