Can you defeat best and second-best?

Jill Shalvis, an author of romance novels, wrote, "Smile. It's the second-best thing you can do with your lips."

Most bridge contracts offer two or more possible lines of play. Then careful analysis will show which is the best line and which is the second-best. Similarly, when a contract can be defeated, there will sometimes be a best defense and a second-best. In today's deal, though, the job for the defenders is to beat the contract whether declarer adopts the best line of play or the second-best.

What can happen after West leads the club king against four spades?