Answer: A. The budget constraint shifts outward.
Explanation:
The budget constraint line shows the possible quantities of a good or service that a person can buy based on their income and the price of the good or service.
Points on the line can therefore be calculated by the formula:
= Income / Price
If the price decreases by 10%, it will lead to a situation where the budget constraint will shift outward because as shown by the formula, the points on the line will increase from having a smaller denominator.