1. Let p, q, r, and s be propositional variables. Which of the following expressions would not be formulas in conjunctive normal form? Why?

(a) p ? p ? p

(b) p ? q ? r

(c) (p ? q) ? (p ? r)

(d) p ? p ? p

(e) p ? q ? p

(f) p ? p ? p

(g) s

(h) (p ? q ? r)

(i) p ? q ? r

(j) (p ? q) ? (q ? r) ? (p ? s) ? (p ? q ? r ? s)

*Please do not copy and paste what is already here on chegg I need the answer but specially the Why?