Final Answer:
The defense mechanism demonstrated in this scenario is B) Projection.
Step-by-step explanation:
Projection is a defense mechanism where an individual attributes their own undesirable thoughts, feelings, or impulses to someone else. In this case, the teenage boy is projecting his feelings of attraction onto the female classmate, assuming that she likes him. The reality may be that these feelings are his own, but he ascribes them to the other person, possibly as a way to cope with the discomfort or anxiety associated with his own emotions. Projection is a common psychological mechanism people employ unconsciously to protect themselves from acknowledging their true feelings.
Option B is the answer.