Which of the following begins the two main parts of a direct proof of a∪(b∩c) = (a∪b) ∩ (a∪c)?
1) a
2) b
3) c
4) a∪b
5) a∪c
6) b∩c
7) a∪(b∩c)
8) (a∪b) ∩ (a∪c)