If 'a' is greater than 1 and is an integer, show that 'n | φ(aⁿ - 1) ', where φ is the Euler's totient function. [Hint: Consider the integers mod (aⁿ - 1) ]
a) n∣(a−1)
b) n∣(a+1)
c) n∣(aⁿ−1)
d) n∣(aⁿ+1)