Sam buys gasoline and coffee each week. To draw his budget line for gasoline and coffee, Sam needs to know
选项：

A:how much income he has to spend on gasoline and coffee, the price of a litre of gasoline, and the price of a cup of coffee.
B:only the price of a litre of gasoline and the price of a cup of coffee.
C:only how much coffee he wants to drink and how much gasoline he needs.
D:only how much income he has to spend on coffee and gasoline.
E:what he needs more—gasoline or coffee.