When her income falls from $50,000 to $20,000, Arianna increases her monthly purchase of hamburger from 20 pounds to 35 pounds. From the midpoint method, Arianna’s income elasticity of demand for hamburgers is options:
A. -1.57.
B. - 0.63.
C. 0.54.
D. - 0.85.
E. 1.57.