Answer:
Option (a) is correct.
Step-by-step explanation:
Here, shoes are normal goods as there is a positive relationship between the income level of the consumer and the quantity demanded for shoes. It can be seen that as the income of the consumer increases from $19,000 to $21,000 then as a result the quantity of pairs of shoes demanded increases from 9 to 11 pairs. Normal goods are generally have positive income elasticity of demand.
Therefore, the shoes are normal goods in this case.