Select all that apply: Which of the following begins the two main parts of a direct proof of A ∪ (B ∩ C) = (A ∪ B) ∩ (A ∪ C)?
a) Assume A ∪ (B ∩ C)
b) Assume A ∪ B
c) Assume A ∪ C
d) Assume B ∩ C