Final answer:
The verb in an essay question that means you should describe the main events, characteristics, or events is 'Diagram'.
Step-by-step explanation:
The verb in an essay question that means you should describe the main events, characteristics, or events is A. Diagram. The word 'diagram' implies the need to visually represent something, rather than providing a detailed description. The other verbs, 'evaluate', 'outline', and 'prove', all imply a different type of response that doesn't involve describing events or characteristics.