The correct answer is A. zero.
The price-consumption curve is a graph that shows how a consumer’s consumption of a good changes as the price of that good changes. If the price-consumption curve is horizontal, it means that the consumer’s consumption of the good does not change at all as the price of the good changes. This is because the consumer is completely indifferent to the price of the good.
The price elasticity of demand is a measure of how responsive consumers are to changes in the price of a good. If the price elasticity of demand is zero, it means that consumers are not at all responsive to changes in the price of the good. This is consistent with a horizontal price-consumption curve.
Options B, C, and D are all incorrect because they all imply that consumers are responsive to changes in the price of the good. This is not consistent with a horizontal price-consumption curve.