First to wanser gets 20

which of the following is an example of an inversely proportional relationship?

a. the more candy bars tyler buys, the higher his total cost will be.
b. the faster mia walks to school, the sooner she will get there.
c. the more light sammy shines on his bean plant, the bigger the bean plant will grow.
d. the lower the rain total at lake sheboygan, the lower the lake's water level will be.