Keep in mind that dividing fractions is the same is multiplying by the reciprocal. The reciprocal of 1/3 is 3/1, or just 3.
The image shows a 4 being divided into 4 groups of 3. When you count the boxes, you can see that there are 12. This means that whatever equation you do, you will want your answer to be 12.
As we stated above, 4 divided by 1/3 is really just 4*3, which equals 12. This confirms that the correct answer is B.
