The correct option is D (a−1)(a+1)(3a+1)(3a−5)
⇒5−(3a2−2a)(6−3a2+2a)
⇒5−(3a2−2a)[6−(3a2−2a)]
Let (3a2−2a)=x
⇒5−x(6−x)
⇒5−6x+x2
⇒x2−6x+5
⇒x2−x−5x+5
⇒x(x−1)−5(x−1)
⇒(x−1)(x−5)
Substituting x=(3a2−2a)
⇒[3a2−2a−1][3a2−2a−5]
⇒[3a2−3a+a−1][3a2+3a−5a−5]
⇒[3a(a−1)+1(a−1)][3a(a+1)−5(a+1)]
⇒[(a−1)(3a+1)][(a+1)(3a−5)]
⇒(a−1)(a+1)(3a+1)(3a−5)