Final answer:
An increase in consumer income would cause a normal good's demand curve to shift to the left.
Step-by-step explanation:
A higher level of income causes a demand curve for a normal good to shift to the right. However, for an inferior good, a higher level of income would cause the demand curve for that good to shift to the left. Therefore, the correct option from the given choices that would cause a normal good's demand curve to shift to the left is a) Increase in consumer income.