Of the Following Explanations, the One That Is Most Satisfactory

Of the following explanations, the one that is most satisfactory from the standpoint of science is .

A) Mary bites her nails because she has masochistic tendencies
B) John never sticks to a diet because he lacks will power
C) Susan is very poor in art because she lacks creativity
D) Harry has stick-to-itiveness because his parents praised him for sticking with projects