John was born into a family that didn't have very much money, and it seemed that his parents struggled to put and keep food on the table. As he grew up, he found school boring despite being smart, so he dropped out. He was always impulsive and finding a job took too long. John recently found out that he is going to be a father and wants to provide the best opportunity for his child that he can. To support himself and his unborn child, he gets involved in selling pain pills and he is arrested in a sting operation. Most researchers would consider this explanation of John's behavior part of the theory.

A. developmental

B. propensity

C. life course

D. trajectory