Assume that a 10% increase in consumer income, ceteris paribus, caused a 4% decrease in the purchase of bus tickets. Based on this information:
a. the price elasticity of demand for bus tickets equals 0.40
b. the price elasticity of demand for bus tickets equals -2.50
c. the income elasticity of demand for bus tickets equals -0.40
d. the income elasticity of demand for bus tickets equals -2.50
d. the income elasticity of demand for bus tickets equals +0.40