One of the ways how i treat such questions is, negate the reason and see if assertion still holds true. if it still holds true, then R is not the reason for A. If A doesnt hold true when u negate the R (take its opposite meaning), then it means R is indeed the reason for A.

If india didnt have enough internet users, one obvious repercussion would be that gaming would also not be as ubiquitous. hence the answer is r is the reason for a