Which of the following numbers will completely divide (4915 - 1) ?

(xⁿ - 1) will be divisibly by (x + 1) only when n is even.

(49¹⁵ - 1) = {(7²)¹⁵ - 1} = (7³⁰ - 1), which is divisible by (7 +1), i.e., 8.