Which of the following statements is true?
a. a decrease in the price of the given good causes an upward movement along the demand curve while a decrease in income causes a rightward shift of the entire demand curve
b. a decrease in the price of the given good causes an upward movement along the demand curve while a decrease in income causes a rightward shift of the entire supply curve
c. an increase in the price of the given good causes an upward movement along the demand curve while an increase in income causes a rightward shift of the entire demand curve
