What is the maximum number of rectangular blocks,each with dimensions 12 centimeters by 6 centimeters by 4 centimeters, that will fit inside rectangular Box X ?
(1) When Box X is filled with the blocks and rests on a certain side, there are 25 blocks in the bottom layer.
(2) The inside dimensions of Box X are 60 centimeters by 30 centimeters by 20 centimeters.

1) there are 25 smal boxes fitted on the bottom layer, but height of box X is not given so it is not possible to say how many small boxes are stacked above each of the 25 boxes.
2) The dimensionof the box X is given , enough to calc. the volume , 60*30*20
The volume of the small box is 12*6*4
Total small boxes fitted = 60*30*20/12*6*4
notice 60/12 = 30/6 = 20 / 4 = 5
so 5*5*5 boxes can be easily fitted.
IMO B