In the following graph, each node represents a computational problem. An arrow like $A->$ F indicates that there is a polynomial time Karp reduction from $A$ to F$.$ Observe that there cauld be more reductions than the ones indicated.

Suppose further that problem $C$ is NP$-$complete. Which of the following statements are true?

$($The exact right option$|$s$)$ must be chosen for this problem to count as solved; no partial points.$)$

Correct Answer

Problow A must be in PSPACE

Correct Answer

Problem B could be in $P.$

Problem D cannot be in CoNP.

Correct Answer

Problem F could be undecidable.

None of the above.

I have the answer for the problem which is in the picture but I don't understand why we have chose this choises and I don't understand graph and how I can use the arrow in the graph to solve the problem.

Can you guide me to which steps I need to think of when I encounter like this problem, because I will get another problem like this but with different graph.