Which One of the Following Boys Exhibits Learned Industriousness

Which one of the following boys exhibits learned industriousness?

A) Joshua would much rather make something with his hands than read a book.
B) Zeke would much rather read a book than make something with his hands.
C) Keith continues to work hard on the computer program he is writing, even though he has not been able to get it to work right yet.
D) Jamal knows that many of the things he is learning in math and physics will be useful in his future career as an architect, and so he studies these topics with possible architectural applications in mind.