According to the Law of Diminishing Marginal Returns

According to the law of diminishing marginal returns:

A) when the amount of some input is increased by equal increments,holding other inputs constant,the resulting increments in output will be negative.
B) when all inputs are increased proportionately,output eventually will decrease at a smaller rate.
C) when the amount of some input is increased at equal increments,holding other inputs constant,the resulting increments in output will eventually decrease.
D) firms will not operate on the portion of the total product curve where marginal product is declining.