Answer:
c. high because buyers generally feel that they can do without it
Step-by-step explanation:
Income elasticity of demand measures the degree of responsiveness of quantity demanded of a product with respect to the change in the income of the consumer, keeping other factors affecting demand as constant.
It is represented as
=

A High income elasticity of demand conveys, a rise in the income of the consumer is accompanied by a higher increase in the quantity demanded. Similarly, a fall in the income of the consumer is accompanied by a greater fall in the quantity demanded.
Caviar fish is expensive and would be usually characterized as a luxury. Thus, if the income of the consumer falls, he will end up forgoing relatively higher quantity of caviar since the consumer believe it to be easier to do away without it.