Indicate which of the following sets are well-defined: A = {blond students in my classroom}, B = {tall men in this meeting}, C = {men who are over 1.75 m tall}, D = {5 pencils}, E = {this eraser, that pen}, F = {an eraser, a pen}, G = {primary colors}, H = {light colors from a sample}, I = {expensive suits}, J = {fast cars}.