Food A has fewer calories per serving.
I found this by taking the first food (A) and dividing 150 by 3. This gave me 50, which I added onto 150 to give me my 4/4 of a serving (200 calories).
With food B, I did the same process. I took 250/2 and added that to the original amount to get the final third of the serving, which resulted in food B being 375 calories.