For each of the letters below, indicate if demand is elastic, inelastic, perfectly elastic, perfectly inelastic, or unitary elastic:

a. Price rises by 10 percent, and quantity demanded falls by 2 percent.

b. Price falls by 5 percent, and quantity demanded rises by 5 percent.

c. Price falls by 6 percent, and quantity demanded does not change.

d. Price rises by 2 percent, and quantity demanded falls by 3 percent.