Your answer would be B. He's talking about not being able to prove his age because he hasn't never seen a real record of his birth or anything else that would give him an idea of how old he is, so no real way to actually prove it.
Explanation:
A adverb is a dependent clause that functions as an adverb.
This means that this part of a sentence could not stand on its own a separate sentence without the independent part of the sentence.
I think it would be
B
I am not 100% sure tho
Harriet the Spy had only one ambition in life, and that was to be a spy.
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She practiced and did research and worked very hard to become one.
Life is a highway by rascal flatts
