let n=6 which are {a,b,c,d,e,f}
2^n=2^6=64 vertices in graph G which all are subset of size 6 : {a,b,c,d,e,f}
Two vertices of G are adjacent if and only if they have exactly 2 elements
so vertex with size 1 : {a},{b},{c},{d},{e},{f}
and vertex with size 0 : { }
cant be adjacent to any vertex
HEnce, number of vertices of degree zero in G is: 6+1=7
in General , n+1
Ans is C