Which of the following is used as a basis for discharge by operation of law when performance is still objectively possible but would be extraordinarily injurious or expensive to one party?
a. frustration of purpose
b. commercial impracticability
c. alteration of the contract
d. anticipatory repudiation
e. anticipatory renunciation

The correct answer is letter B.

Explanation:  Impossibility is an excuse for not fulfilling obligations under a contract, based on a change of circumstances (or a discovery of pre-existing circumstances), an occurrence that was an underlying assumption of the contract, which causes execution of the contract literally impossible.

This can be solved with an equation.

 

now, as far as I can tell this question was made multiple choice for a reason; just start to plug in numbers. So using the answers x is either equal to 1 or 2. lets try and solve the equation plugging 2 in. When you solve for this you end up with  none of your answers have one where y<2 so x must be 1. so lets solve for x=1.
you end up getting 

The only answer where x=1 and y<4 is C sos c is your answer. Hope this helped! :)