Explain: In triangles abc and def, angles a and b each have measure 60°, ac = 10, and rt = 30. Which additional piece of information is sufficient to prove that triangle abc is similar to triangle def?

A) bc = 7 and ef = 7

B) bc = 7 and ef = 21

C) The measures of angles b and e are 70° and 60°, respectively.

D) The measures of angles b and f are 70° and 50°, respectively.