Answer:
Rehearsal technique
Step-by-step explanation:
Rehearsal is a mental technique which involves repeating a particular information several times in other to enhance the retention to memory of such information and enabling easy recall of such information later on when needed.
In order for Katie to remember the phone number said by her mum, she commits the umber to memory by repeating it to herself, which enables her to easily recall after her mum ends the call.