Sorry for such late an answer, but I believe its A) Predicate Nominative.
Answer:
I think the answer is
A. formal, serious, shy, closed, uncertainty, exhaustion, confusion
B. He's good natured and possibly making a joke
The purpose of exposition (or expository writing) is not primarily to amuse, but to enlighten and instruct. The objective is to explain and analyze information by presenting an idea, relevant evidence, and appropriate discussion. Its essential quality is clarity.
The answer is A thank me later