Your Sister Always Brags About How Savvy of a Grocery

Your sister always brags about how savvy of a grocery shopper she is.She believes that she saves lots of money from paying with coupons and making her grocery purchases at multiple stores to get the lowest prices on all goods.She may overestimate her savings because:

A) she does not count the value of the time it took to sort and clip coupons as a cost.
B) she does not count the cost of the gas used driving extra miles to multiple grocery stores.
C) she does not count the value of the extra time it takes standing in multiple lines at multiple stores,using multiple coupons,rather than a trip to one store with no coupons.
D) All of these.