The Amount in Dollars, A, Spent Weekly by a Household

Multiple Choice

The amount in dollars, A, spent weekly by a household on food is a function of the household's weekly income in dollars, I, and the number of people in the household, n. Thus, . If A_I (1000, 4) = a > 0, then which of the following is true?

A) At a weekly income of $1000 and a household size of 4, an increase of 1 person in the household produces a decrease of $a in the amount spent weekly on food.
B) At a weekly income of $1000 and a household size of 4, an increase of $1 in weekly income produces a decrease of $a in the amount spent weekly on food.
C) At a weekly income of $1000 and a household size of 4, an increase of 1 person in the household produces an increase of $a in the amount spent weekly on food.
D) At a weekly income of $1000 and a household size of 4, an increase of $1 in weekly income produces an increase of $a in the amount spent weekly on food.