Start by recalling the definitions of P and NP-complete problems, and consider how each of the given problems (sorting, MST, max clique, 3-coloring, shortest path) fits into these categories.

For each problem, analyze whether a solution can be verified in polynomial time (a key trait of NP problems) and whether a polynomial-time algorithm is known (P problems).

Focus on the problems that are not known to be in P (like max clique and 3-coloring) and recall known reductions or proofs that classify them as NP-complete, while confirming that sorting, MST, and shortest path are in P.