15. List the ordered pairs in the equivalence relations produced by these partitions of (a, b, c, d, e, f, g}. a.{a,b}, {c,d}, {e, f, g} b. {a}, {b}, {c, d}, {e, f}, {g} c.{a, b, c, d}, {e, f}, {g} d. {a, c, e,g}, {b,d}, {f}