In an experiment to compare the effects of two different growing conditions on the heights of greenhouse chrysanthemums, all plants grown under condition 1 were found to be taller than any of those grown under condition 2 (i.e., the two height distributions did not overlap). Calculate the value of Us and find the P-value if the number of plants in each group was
(a) 3
(b) 4
(c) 5
(Assume that HA is non-directional.)