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8. Let X1, X2 be a random sample of size n = 2 from a population having gamma distribution with probability density function f(xla,) = () ga e x-1, x2 0, where a > 0 and 0 > 0 are unknown parameters, and I(a) is the usual gamma function. (a) Show that T = (X1 + X2, X1X2) is a minimal sufficient statistic; (b) Are T, = (| In(X,X2l, X1 + X2) and T2 = (InX, + InX2, In(X, + X2)) sufficient statistics; here, for any real number x, Ix| denotes the modulus of x; (c) Find the minimum variance unbiased estimator of V(X,)