If a and a" are both generators of a cyclhe group of order n, then (a) n must be prime (b) n must not be prime (c) n must be odd (d) n must be even nlin roup of

If a and a" are both generators of a cyclhe group of order n, then (a) n must be prime (b) n must not be prime (c) n must be odd (d) n must be even nlin roup of order 40.