If the quantity demanded from good X has increased from 40 to 50 units as a result of the increase in the consumer income from OR 400 to 500, the income elasticity of demand for good X is:
Select one:
a. 1, and the good is normal
b. 1, and demand is unitary elastic
c. 0.1, and demand is elastic
d. 0.1, and the good is inferior