How to solve this problem?

4. Let X1, ..., Xn be a random sample from N(u, 1). Define Ti = (X,) and T2 = {n(n -1)}-Exitin XiX; as two estimators of , where Xn = n-1 )_ Xi. (a) Show that both Ti and T2 are consistent for u2. (b) Find the asymptotic distributions of T1. (c) (Optional) Find the asymptotic distributions of T2