Need help with this economics question please!?

Question

Max has utility function U = xy, with marginal utility MUx = y and MUy = x. His budget constraint can be written pxx + pyy = I. What is Max's demand curve for x?

a) pxx = pyy

b) x = I/2px

c) xpx = ypy

Answer 1

MUy/MUx = py/px=x/y so the answer is c) that is he will spend equal amounts on x and y. But what does a) mean. do you have a typo???