When total utility is maximum, marginal utility becomes ___________.

A)

zero

B)

unity

C)

positive

D)

negative

Total utility is the sum of all marginal utilities derived from consumption of each additional unit of a commodity. When marginal utility is zero, the consumer derives no further utility from consumption and any further consumption will lead to negative marginal utility. Thus, the total utility is maximum at this point and any further consumption of that commodity will lead to a diminishing total utility.