Which of the following is an example of conservation?

group of answer choices
a. joseph saves his energy by brushing his teeth in the shower.
b. rebekah recycles her glass bottles but not her cell phone batteries.
c. scott knows that one piece of pizza cut into two slices is the same amount as cutting the same piece of pizza into three slices.
d. deirdre believes that five pennies have more value than two nickels.