In Problem 1, If Charlie's Utility Function Were X⁵_AX_B, If

In Problem 1, if Charlie's utility function were X⁵_AX_B, if apples cost 50 cents each, and if bananas cost 10 cents each, Charlie's budget line would be tangent to one of his indifference curves whenever

A) 5X_B = 5X_A.
B) X_B = 5X_A.
C) X_B = X_A.
D) X_A = 5X_B.
E) 50X_A + 10X_B = M.