Last Year, Housam Purchased 60 Kilos of Potatoes to Feed

Multiple Choice

Last year, Housam purchased 60 kilos of potatoes to feed his family of five when his household income was US$30,000. This year, his household income fell to US$20,000 and Housam purchased 80 kilos of potatoes. With all else constant, Housam's income elasticity of demand for potatoes is

A) positive, so Housam considers potatoes to be a normal good and a necessity.
B) negative, so Housam considers potatoes to be an inferior good.
C) positive, so Housam considers potatoes to be an inferior good.
D) negative, so Housam considers potatoes to be a normal good.