Which statement shows that money is a “ measure of value” (a. this bill is worth twenty dollars. ) (b. my mp3 player is worth twenty dollars. ) (c. the dollar is just found in my drawer is still worth a dollar. ) ( d. the more gigabytes it has, the more it is worth)

the answer is B. My MP3 player is worth twenty dollars.
Money as measure of value means that It could be use to measure the value of a certain products or services that you needed.
This type of measurement usually relied on economic condition and quality of the products/services.