If an individual’s utility function for coffee (x) and cream (y) is given by U(x, y) = min (x, y), and I is the disposable income, the demand function for coffee is given by
选项：

A:X = I/2px.;
B:X = I/(px + py).;
C:X = I/(px + 0.2py).;
D:X = I/2 (px + py).