Answer will be Option (C).
1. Yes, Best possible Time Complexity for "Comparison based" Sorting Algorithm is $\Omega(N log N)$. It's proof is based on number of permutations we can get. You can read here.
2. Yes, we can certainly implement so that stability is guaranteed even though the default procedure don't. We might increase time complexity, but, it's certainly possible.
3. Yes, Counting Sort is NOT comparison based sorting Algorithm.
4. No, Heap Sort is comparison based. We compare in the heapify function.
So, Option (C).