If prism a is similar to prism b and the volume of prism a is 2720 cm^3. all answers are possible depending on the scale factor of the similar prisms. we can try each of the choices, one by one.
if the scale factor is 1/8, the answer is 21,760 cm3
2, the answer is 1360 cm3
4, the answer is 680 cm3
8, the answer is 340 cm3