Ben gets utility from apples and bananas and his preferences can be represented by the utility function U(A,B)=4A+B. If the price of apples is 3 times the price of bananas, what is Ben's ordinary demand function for apples, A*(pA, pB, I)?
A*(pA, pB, I)=2I/pA
A*(pA, pB, I)=I/pA
A*(pA, pB, I)=0
A*(pA, pB, I)=I/(3pA)
A*(pA, pB, I)=I/(4pA)