When marginal utility is zero, then total utility will be :

Maximum

The correct answer is option (1) : Maximum

1. When the marginal utility is zero, the total utility is at its maximum.

2. This is because the marginal utility measures the change in total utility with respect to a one-unit change in the quantity of a good consumes.

3. When the marginal utility is zero, it implies that the total  utility is neither increasing nor decreasing, indicating that the consumer has reached the point of maximum satisfaction or equilibrium for the quantity consumed.

Therefore, the correct options is (1) Maximum.