What Is the Most Likely Reason That Snack Foods Sold

What is the most likely reason that snack foods sold in vending machines are so much more expensive than snack foods sold in grocery stores?

A) Snack foods sold in vending machines come in smaller packages, so the per-package costs are higher.
B) Grocery stores buy in bulk, while vending machine companies tend to buy in smaller quantities.
C) People who purchase snack foods from vending machines tend to have less elastic demand for snack foods.
D) Owners of vending machine companies are greedier than owners of grocery stores.