I have a quistion regarding the below: If the price of a complement for tires decreases, all else equal, a.quantity demanded for tires will...

I have a quistion regarding the below:

If the price of a complement for tires decreases, all else equal, 

a.         quantity demanded for tires will decrease.

b.         quantity supplied for tires will decrease.

c.         demand for tires will increase.

d.         demand for tires will decrease.

e.         supply for tires will increase.

Answer: c

Q: I know that the Answer is C but I also know that that supply should decrease. So why isn't "B" a correct answer as well?

Thank you,