Assignment:
Which of the following is true.
a) 16 is a non-trivial square root of 1 modulo 51; hence 51 is composite
b) 7 is a non-trivial square root of 1 modulo 47; hence 47 is composite
c) 8 is a non-trivial square root of 1 modulo 55; hence 55 is composite
d) all of the above
e) None of the above