How many choices exist at trick one?

J.K. Rowling said, “Destiny is a name often given in retrospect to choices that had dramatic consequences.” In this deal, South has choices at trick one. He is in seven spades, and West leads the diamond king. How many options does South have, and what would happen after each? South also had choices in the auction. After North opened one heart, South reasonably chose to respond five no-trump, the Grand Slam Force, asking his partner to bid seven with two of the top three heart honours. When North did exactly that, South converted to seven spades. North then contemplated bidding seven no-trump based on his diamond ace, but it was lucky that he did not. South had three choices at trick one (if we ignore the absurd play of ruffing the diamond ace). He could win with the diamond ace and discard either a club or a heart, or he could play low from the board and ruff in his hand. When I run this deal in a class, (almost) everyone discards the club five and can no longer make the contract when the hearts are 4-0. Much better is to throw a heart on the diamond ace. Then, after drawing trumps and turning to hearts, South can ruff the fourth round, cross to dummy with a spade and pitch his club five on the heart six. My preference, though, is to ruff at trick one. Then, when the bad heart break is revealed, declarer will see the necessity to discard a heart, not a club, on the diamond ace. Carefully consider your choices.