Answer:
option (C) 16
Step-by-step explanation:
Data provided in the question:
Utility function is

Number of tapes

Number of tape recorders
Amount of money
Left to spend

is 1 or greater.
The price of tapes is $1
The question states that she has one tape recorder. i.e.,

which means that
(since
then


and

we take

condition for utility maximizing is.





Hence, answer is option (C) 16