Plaese help in the next question:

You are managing a project and the customer’s engineer visits your facility on an inspection and general getting acquainted tour. During the tour they make the comment that the parts that are being designed should be in stainless steel instead of plain steel with enamel. What should you do?

a. Authorize the change in design to your engineers
b. Continue with the present design
c. Speak to the visiting engineers and discuss having an informal meeting between your engineers and the visiting engineers
d. Ask the visiting engineers to submit a change proposal to the change system

the right answer supposed to be (c) instead of (d). Why ??