Bentley had $40 in birthday money in her piggy bank. She spent $10 on new flip-flops, then got $20 for her allowance and did not spend any of that money for 1 week. Finally, she spent $15 on new sunglasses.

Which part of the scenario is best represented by a linear increasing interval?

A. Bentley has $40 in her piggy bank.
B. Bentley spent $10 on new flip flops.
C. Bentley got $20 for her allowance.
D. Bentley spent $15 on sunglasses.