For which of the following sets of hypotheses is a lower (left) tail test indicated?

a. H₀: m = 10; H_a: m (is not equal to) 10

b. H₀: m 10; H_a: m < 10

c. H₀: m 10; H_a: m > 10

d. possibly (a) or (b), but more information is needed to tell conclusively.