In Problems 1–6, let U = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}, A = {1, 3, 5, 7, 9}, B = {2, 4, 6, 9, 10}. Find:

Replace the question mark with one of the symbols =, ⊂, ⊆, or ∈ to make the statement true.

a. {2} ? B

b. 2 ? B

c. ∅ ? { }

d. {5, 3, 7, 9, 1} ? A

e. B ? U