Answer:
B. 2 blocks per cubic inch
Explanation:
The volume in cubic inches is the product of the dimensions in inches. The ratio of blocks per cubic inch is found by dividing the number blocks by the number of cubic inches. (Effectively, "per" means "divided by".)
(240 blocks)/((6 in)(4 in)(5 in)) = 240/120 blocks/in³ = 2 blocks/in³