Answer:
B. Retroactive interference
Step-by-step explanation:
Retroactive interference can be referred to as a condition in learning whereby there is an interference between new learning/knowledge and old knowledge. For example an actor while learning a script for a play, might forget previously learnt script. Learning a new task would make a person to forget what he has learnt previously.
Relating this to this question,Chris forgets the names of his students in the previous semester after he has learnt the names of his students in the new semester.