Task: Question Answering
Input (English): Question: Three grades of milk are 2 percent, 3 percent and 5 percent fat by volume. If x gallons of the 2 percent grade, y gallons of the 3 percent grade, and z gallons of the 5 percent grade are mixed to give x+y+z gallons of a 4 percent grade, what is x in terms of y and z?

 Option A: y + 3z

 Option B: (y +z

 Option C: 2y + 3z

 Option D: z/2

 Option E: 3y + 4.5z
Output (English): Option D