Use proof by contradiction to show that for all integers m, 7m + 4 is not divisible by 7.
a) Assume 7m + 4 is divisible by 7, then show contradiction based on m being an integer.
b) Assume 7m + 4 is divisible by 7, then show m cannot be an integer.
c) Assume 7m + 4 is not divisible by 7, then prove it for all m integers.
d) Assume 7m + 4 is divisible by 7, then prove it for all m integers.