The reason General Motors got into trouble with a supplier was that a. It increased volumes so much that the supplier was no longer profitable.
In order to gain more customers, General Motors began demanding more trim in its vehicles.
Trim, which refers to including a lot of features in a car to make it more attractive, can be expensive to make. When General Motors made the supplier produce a lot of it, the supplier stopped making profit.
In conclusion, option A is correct.
Find out more on trim in cars at https://brainly.com/question/394939.