Oliver is trying to make an online purchase, but he does not have his credit card. he calls his wife, who reads out the 16-digit credit card number to him. unfortunately, oliver cannot remember the number long enough to type it into the computer. this is because:

Short term is constrained in length and limit  

Explanation:

Short term memory also referred to as active or primary memory is the limit with regards to holding, however not controlling, a modest quantity of data at the top of the priority list in a functioning, promptly accessible state for a brief time frame. For instance, short term memory can be utilized to recall a telephone number that has quite recently been presented.

This is the reason why Oliver can't remember the number.

Short term memory.

Explanation:

Memory may be defined as the ability of an individual to remembers the incidents. Two main types of memory are the long term memory and the short term memory.

Oliver tries to remember her wife credit card number but forget it. This is a type of short term memory. The short term memory remain for only few periods of time and later get vanish with time. Hence, his short term memory removes the memory of credit card number.

Thus, the answer is short term memory.