Question

The Egyptologist, who had worked with the business person, was convinced that King Tut's tomb was in the Valley of the Kings.

Answer 1

Since nothing is underlined, I am going to make an educated guess that the underlines clause is "who had worked with the business person". If that is the case, the correct answer would be D - adjective clause. It is a relative clause, to be more precise, because it starts with a relative pronoun "who", but that is a part of adjectival clauses, so that is the correct answer.