Final answer:
The context clue used to determine the meaning of 'officious' in the provided text is an example context clue, as the sentence gives a specific instance of Diana's behavior.
Step-by-step explanation:
The type of context clue used in the text to help determine the meaning of the word 'officious' is D) Example context clue. The sentence 'For instance, she was always involved in other people's business' provides a direct instance or example of how Diana behaves, which in turn helps to clarify the meaning of 'officious'. The use of specific examples to define or elucidate a word is typical of example context clues.