Can't seem to find the answer to this question.

In the aftermath of WWI, the largest manufacturing industry in the state of California was?

a. canning industry
b. auto industry
c. agriculture
d. petroleum

e. none of the above.

2 answers

The center of the auto industry was Michigan. Agriculture and petroleum are not manufacturing industries. That leaves only one possible answer.
Canning and Petroleum are manufacturing industries is what MsSue meant.