and why?

3. Are the following regular or not? a. a"bn+1 n >= 0 b. a'bm m >= 2n C. {walwl | w in (alb)*} d. {www w in (alb)*} (any w, followed by equal number of a's) P = {w | w in (alb)*, w = wR} (palindromes over a,b) d. P e. PP = (xy | x,y are in PAL}