The correct answer is: The shop would shift production to oil changes and away from brake checks.
When the mechanic shop offers a discounted oil change, it may lead to an increase in demand for oil changes and a decrease in demand for brake checks. In order to meet this increased demand for oil changes, the shop will likely shift its production towards oil changes and away from brake checks. This shift in production will be reflected on the production possibilities curve as a movement from the current production point towards a point with a higher quantity of oil changes and a lower quantity of brake checks.