Final answer:
After subtracting the 12 baseballs that rolled away from Allie's original 24 baseballs, she is left with 12 baseballs.
Step-by-step explanation:
To solve how many baseballs Allie has left, we perform a simple subtraction operation. Allie initially had 24 baseballs and 12 rolled away. By subtracting the number of baseballs that rolled away from the original amount, we get the number of baseballs remaining.
24 original baseballs - 12 rolled away = 12 baseballs left.
Therefore, the correct answer is A) 12 baseballs.