Question

The main factors that determine quantity supplied are price and _____.

A. consumers' preferences
B. costs of productive resources
C. population growth

Answer 1

I say the answer is b

Answer 2

The factors that determine the supply of a good are the costs of production and the profit margin, which is the difference between cost and selling price.

Consumer preferences determine demand, which is also affected by price.

Addition: realize that the price determines both supply and demand. This is because in an economy with competition, the price is given by the interaction between supply and demand.