The answer is a medium Pizza of 12 inches radius.
The formula for finding the area of a square is pir^2(sorry but my phone won’t let me write pi in its symbol form). If we substitute 3 for pi, then that would the 3r^2. Then we would substitute the potential answer choices until we reach one that is closest to 400 in^2. For the small pizza, that would be 9*9*3, which is also 243 inches square. For the medium pizza, that would be 12*12*3, which is also 432 inches square. Finally, for the large pizza it is 15*15*3, which is 675. Therefore, the medium pizza has an area closest to inches square.
