The correct answer is Very young owls grow slowly.
Here, the adverb is <em>very </em>and the adjective is <em>young, </em>so the adverb is used to modify the adjective, or to show a particular degree of the adjective (how young? very young.).
In the rest of the options, there is only one adverb <em>slowly, </em>and it's not modifying an adjective, but rather the verb.
Exposition
is your answer :D
I would answer nesting dolls.
D. "his sister, who had taken a sales job, learned shorthand and French in the evenings so that she might be able to get a better position later on"