The correct answer is D, 'Subtract 42 - 12. Then divide the difference by 3'. Lauren has 42 muffins, and she can put 12 of them into a box, leaving her with 30 muffins to fit into bags. If she can fit 3 muffins in each bag, and she wants to know how many bags she needs, then she needs to divide 30 by 3 to get 10. This means that she will need 10 bags of 3 muffins to completely pack 30 muffins. She started with 42, but 12 of those fit into the original box, so we don't have to worry about it.
Hope this helps!