Answer: A. Something difficult to understand or define
Explanation: The general definition of elusiveness is "eluding or failing to allow for or accommodate a clear perception or complete mental grasp". This applies to the paragraph because they are saying the path to success is unclear.
That seems like a fragment
I think you should combine c and d if possible, if not then a is the best answer in my opinion.
Answer:
Explanation:
It is effective because the comparaison is relevant and the technical vocabulary is used clearly
Answer:
A.to provide basic facts and ideas about a topic
Explanation: