Context clues are little clues left in a text that allow you to infer the or come up witht he meaning of a certain word by reading the text and providing you with context, there are 4 kind of context clues:
Synonim, Antonym, Explanation, or Example.
In this case, the text uses words taht mean the same or are close to the meaning of Vapid to help you understand the word, Dull, Bored, are closely related to Vapid which means flat or with nothing interesting, that´s why the answer is Synonym.
A relative pronoun is a kind of pronoun that is used to link a clause or phrase (adjective) to a noun or pronoun. In this sentence, the relative pronoun is the word "who". The relative pronoun "who" links the noun "people" to the adjective phrase "fascinated with King Tut".