Beth Consumes Two Goods, X₁ and X₂, and Her Income

Beth consumes two goods, x₁ and x₂, and her income is $120. The price of x₁ is $10, and the price of x₂ is $5. If her indifference curves exhibit a diminishing marginal rate of substitution and if her marginal rate of substitution at bundle (7, 10) is 1, then her utility maximizing bundle is:

A) (7, 10) .
B) (6, 12) .
C) on the budget line to the left of (7, 10) .
D) on the budget line to the right of (7, 10) .