Final answer:
The correct notation that represents spending $2.50 on 10 apples is C(10) = 2.50.
Step-by-step explanation:
The correct notation that represents spending $2.50 on 10 apples is b) C(10) = 2.50.
In this notation, C(10) represents the cost of buying 10 apples, which is equal to $2.50.
C(n) represents the cost of buying n apples, so C(10) = 2.50 indicates that the cost of buying 10 apples is $2.50.