If you were given access to the 2 possible questions prior to the exam date, then perhaps developing an essay response targeting each question is the better option since both essays will constitute direct responses to their respective question. Also, considering school has not yet started, you should have sufficient time to effectively develop, refine and memorise those essays.
While developing analyses and adjusting them depending on the essay question by modifying a few words may yield favourable results (depending on what your goals are), they may not provide a sufficiently direct response that specifically targets a particular question. On the other hand, it is known that an essay response, the analysis of which was developed in such a way that it directly responds to the important aspects raised by a particular question, allowing for a higher quality response and therefore a more favourable result.
I hope this helps!