GMAT Critical Reasoning (CR) | Re: Over an eleven-month period, during which national retail co

Since the no. of months is not determined by the phrase "ensuing months", option A is possible if the "ensuing months" is not equal to 4 months.

Nonetheless, D may also be true - implementation of X may just be coincidental and not causal. It is possible that some other regulation Y was implemented and that caused this change in market scenario.

So, in my view all options could be true.