Which sentence presents an alternative in appropriate way?

a. "The 11 a.m. flight is completely sold out, so I booked you on the 2 p.m. flight. Hopefully that will work for you."

b. "We are out of the red units, so we went ahead and shipped you 12 green ones instead. You can return them if they do not meet your needs."

c. "It turns out the problem is bigger than we thought; the entire compressor needs to be replaced, not just the belt. We can either replace it with a new or refurbished part, or you may opt to purchase a whole new machine."

d. "The warranty period expired yesterday, so there is no choice but to pay the $119 charge to have the unit repaired."

And your answer?

I am pretty sure it is c but I am not sure if it would be a or c.

I'd much rather hear a than c.

A is the wrong answer

The sentence that presents an alternative in an appropriate way is option C: "It turns out the problem is bigger than we thought; the entire compressor needs to be replaced, not just the belt. We can either replace it with a new or refurbished part, or you may opt to purchase a whole new machine." This sentence offers different choices or alternatives for addressing the issue with the compressor, allowing the listener to make a decision based on their preferences or needs.