Please help with an economics question.

State whether each of the following events will result in a movement along the demand curve for McDonald's Big Mac Hamburgers or whether it will cause the curve to shift.

The price of fries increases due to a potato shortage. This will:
a. Decrease the demand for McDs Bigs Mac hamburgers.
b. Increase the demand for McDs Big Mac hamburgers.
c. Cause a movement along the demand curve for McDs Big Mac hamburgers