The correct option is
A True
⇒am−n.bn−1.c1−m=1
As given a=xm+n.y1;b=xn+1.ymandc=x1+m.yn
Put the value of a,b,c in LHS
⇒(xm+n.y1)m−n.(xn+1.ym)n−1.(x1+m.yn)1−m
⇒xm2−n2.ym−n.xn2−1.ymn−m.x1−m2.yn−mn
⇒xm2−n2+n2−1+1−m2.ym−n+mn−m+n−mn
⇒x0.y0 ∵[x0=1]
⇒1×1=1
So LHS=RHS
The given statement is true.