Need Help asap if you know the answer please explain so i know your not guessing! thank you

find the volume of the rectangular prism.
A) 21 m3
B) 42 m3
C) 240 m3
D) 480 m3

Need Help asap if you know the answer please explain so i know your not guessing thank you find the volume of the rectangular prism A 21 m3 B 42 m3 C 240 m3 D class=