Factor by Using Substitution $8 v ^ { 4 } - 31 v ^ { 2 } + 21$

Multiple Choice

Factor by using substitution. $8 v ^ { 4 } - 31 v ^ { 2 } + 21$

A) $\left( 8 v ^ { 2 } - 7 \right) \left( v ^ { 2 } - 3 \right)$
B) $\left( 8 v ^ { 2 } - 3 \right) \left( v ^ { 2 } - 7 \right)$
C) $\left( 8 v ^ { 2 } + 7 \right) \left( v ^ { 2 } + 3 \right)$
D) Prime