The correct answer is: A. Increases.
Marginal utility is the additional satisfaction or benefit that a consumer receives from consuming one more unit of a good or service. Total utility is the total satisfaction or benefit that a consumer receives from consuming all units of a good or service.
When marginal utility is positive, it means that the consumer is still receiving some satisfaction or benefit from consuming more of the good or service. This means that total utility is still increasing.
When marginal utility is negative, it means that the consumer is receiving less satisfaction or benefit from consuming more of the good or service. This means that total utility is decreasing.
When marginal utility is zero, it means that the consumer is receiving the maximum amount of satisfaction or benefit from consuming the good or service. This means that total utility is at its maximum.
Therefore, the correct answer is: A. Increases.