Let $G$ be a simple graph with $20$ vertices and $100$ edges. The size of the minimum vertex cover of G is $8$. Then, the size of the maximum independent set of $G$ is:
Vertex cover: A set of vertices such that each edge of the graph is incident to atleast one vertex of the set.
Therefore, removing all the vertices of the vertex cover from the graph results in an isolated graph and the same set of nodes would be the independent set in the original graph.
size of minimum vertex cover = 8
size of maximum independent set = 20 - 8 =12
Therefore, correct answer would be (A).
Reference :- http://mathworld.wolfram.com/MaximumIndependentVertexSet.html