Answer: Cue-dependent forgetting
Explanation: Cue-dependent forgetting could be explained as a type of memory failure whereby an individual fails to recall an information from memory due to the absence of the stimulus or cue used or present at the time of encoding the information.
In the scenario above, Dr. Roger's is unable to remember or recall the name of his student most probably due to the fact that the stimulus present at the time of encoding the students name in memory isn't available, thus cue is probably the classroom environment, which explains why she immediately recalls the student's name when he sees her in class.