Exercise 3 (2 pts). The SPARSE SUBGRAPH problem is defined as follows: Input: ?G, p, q? where G is a graph and p, q e z. Question: Does G have p vertices such that there are at most q edges between them? Prove that this problem is NP-hard by giving a polynomial-time reduction of INDEP-SET (known to be NP-hard) to SPARSE SUBGRAPH Hint. Any independent set of size k can be viewed as a "sparse subgraph" consisting of k vertices with no edges between them