Carla Has Become Very Busy Since She Came to College

Carla has become very busy since she came to college. She is a full-time student and is very active in campus clubs and organizations. Her classes and campus activities leave her little time to socialize with her friends. She is beginning to feel that she has let her friends down because she has had to cancel several activities they had planned, but she also feels guilty if she isn't able to meet her other obligations. Carla has always thought that she was in control of her life and has managed well up until now. She wants to spend more time with her friends without giving up her other activities.
-Carla made a plan to spend more time with her friends but found that her plan didn't seem to be working well.Which of the following is the most likely reason that Carla's plan is not working as she expected?

A) Carla made a plan before monitoring and evaluating her schedule.
B) Carla is not adequately motivated to change her behavior.
C) Carla is more committed to her activities than to her friends.
D) Carla has an external locus of control.