Luis always has good intentions when it comes to studying. However, he tends to put off studying ...

Luis always has good intentions when it comes to studying. However, he tends to put off studying until the last minute, and then he is usually too tired to do the work. Often he sits down to study and a friend from down the hall comes in and wants to chat. Before long, Luis and his friend are going out and Luis has forgotten all about the test scheduled for the following day. This scenario suggests that Luis lacks which one of the following traits of confident students?
 
  A. enthusiasm
  B. flexibility
  C. self-management
  D. sociability