Your customer requested that the new railroad cars you are building for his company is constructed from heavy grade aluminum. After reviewing the requirements, two of your experts inform you that your customer would be better off with steel cars. You meet with the customer to discuss your team's findings, and he informs you to go ahead with the aluminum cars. What should you do?

a. Provide aluminum cars that meet the customer's requirements.

b. Find a way to cut the costs and upgrade the cars to steel.

c. Meet the customer again to ensure he understands the expert opinion about using steel instead of aluminum.

d. Meet with your experts to find another proposal for the customer.