As a result of the machine being able to double production of baseballs and bats, the curve would expand on both axes.
If a machine is invented that can produce more bats and balls, the curve will expand on both axes as the curve represents the maximum quantity that can be produced of either and if they increase, the curve will as well.
In conclusion, option C is correct.
Find out more about the production possibilities curve at https://brainly.com/question/2601596.