Answer:
See below ....none of your answer choices 'fit'
Explanation:
Break it into two pieces....a triangular prism and a square pyramid
prism volume = (area) * length
( 1/2 base * height) * length
Use pythagorean theorem to find height of triangular prism = 12
1/2 * 12 * 9 * 21 = 1134 km^3
Pyramid volume = 1/3 base * height =
= 1/3 * (9*21) * 7 = 441 km^3
Summed = 1575 km ^3