Assume that Alex's marginal propensity to consume equals 0.8, and that in 2004 Jane spent $36,000 from her disposable income of $40,000. If her disposable income in 2005 increased to $50,000, her consumption spending increased by:
a. $4,000
b. $8,000
c. $9,000
d. $10,000
e. $14,000
