When milk consumption decreased, a survey firm wanted to know what was going on, so they interviewed people and found that people thought that rising...

When milk consumption decreased, a survey firm wanted to know what was going on, so they interviewed people and found that people thought that rising milk prices were making it hard to justify their milk purchases. This suggests that what is going on is a:

A: movement for the demand curve for milk

B: shift of the supply curve for milk

C: movement along the supply curve for milk

D: shift of the demand curve for milk