The correct option is D |Δ|=1
Consider, Δ2=∣∣
∣∣l1m1n1l2m2n2l2m3n3∣∣
∣∣∣∣
∣∣l1m1n1l2m2n2l2m3n3∣∣
∣∣
=∣∣
∣
∣∣l21+m12+n12l2l1+m2m1+n2n1l3l1+m3m1+n2n1l2l1+m2m1+n2n1l22+m22+n22l3l2+m3m2+n2n3l3l1+m3m1+n2n1l3l2+m3m2+n2n3l23+m32+n32∣∣
∣
∣∣
=∣∣
∣∣100010001∣∣
∣∣
⇒Δ2=1
⇒Δ=±1
⇒|Δ|=1