<p>the correct answer is D, but I am confused between D and E. agile could mean quick, graceful, smart, or clever, which fit in the sentence. so why E is wrong ???</p>
<p>Yes, but the question refers to the usage of tools. A person or an animal can become agile by themself/itself. However, to become skilled at using tools, one becomes adept.</p>
<p>Answer is D.
E is incorect because agile means that something can easily move.
Adept is correct because adept means that one is skilled at something.</p>