Suppose that we wish to test H0 :p1 -p2 =0 vs. Ha: p1 -p 2 >0. Random samples of n 1 =100 and n 2 =160 yielded sample proportions of hat p 1 =0.35 and hat p 2 =0.25. The value of the test statistic to test H0 is A. 1.78 b. 1.70 c. 1.645 d. 1.73 e. 1.96