Pam Entered into a Contract with Dave

Pam entered into a contract with Dave.A court will declare that the contract was frustrated if

A) Dave promised to keep Pam's sidewalks clear of snow for a flat fee of $500 for the winter, but now wants to escape the contract because the city has already been hit by six major blizzards and it is only the middle of January.
B) Pam repaired Dave's truck, but before he could resume possession, the vehicle was destroyed by a fire of unknown origin.
C) both parties performed as promised, but neither party is satisfied with the end result.
D) Dave stored Pam's household goods while she was attended school in Spain for a year, but he now refuses to allow her to take possession of the property unless she pays storage fees.
E) neither party realized, when they created the contract, that they would both have to pay a tax on the transaction.