1. Diego drank x ounces of juice.
Lin drank 1/4 less than that.
That means that for every ounce of juice Diego drank, Lin drank 1 - 1/4 = 3/4
So, the correct is letter B.
2. Lin ran x miles.
Diego ran 3/4 more than that.
That means that for every mile Lin ran, Diego ran 1 + 3/4 = 7/4
So, the correct is letter A.
3. Diego bought x pounds of nuts.
Lin bought 1/4 of that.
That means that for every pounds of nuts Diego bought, Lin bought 1 * 1/4 = 1/4
So, the correct is letter C.