If Charlie's Utility Function Were X ⁶_A X_B and If

Multiple Choice

If Charlie's utility function were X ⁶_A X_B and if apples cost 40 cents each and bananas cost 10 cents each, Charlie's budget line would be tangent to one of his indifference curves whenever

A) 6X_B = 4X_A.
B) X_A = 6X_B.
C) X_B = X_A.
D) X_B = 6X_A.
E) 40X_A + 10X_B = M.