(a) Find all solutions of the equation a^2 ≡ 1 (mod 8), for a ∈ {1,2,...,7}.
(b) Let p be a prime number and a ∈ {1,2,...,p-1}. Determine whether the following statement is true or false, and provide a justification for your answer:
If a^3 ≡ 1 (mod p), then a ≡ 1 (mod p).