Factor the Polynomial by Substitution $$15 z ^ { 4 } + 2 z ^ { 2 } - 8$$

Multiple Choice

Factor the polynomial by substitution.
- $$15 z ^ { 4 } + 2 z ^ { 2 } - 8$$

A) $\left( 5 z ^ { 4 } + 4 \right) ( 3 z - 2 )$
B) $\left( 3 z ^ { 2 } + 2 \right) \left( 5 z ^ { 2 } - 4 \right)$
C) $\left( 3 z ^ { 4 } + 2 \right) ( 5 z - 4 )$
D) $\left( 5 z ^ { 2 } + 4 \right) \left( 3 z ^ { 2 } - 2 \right)$