ZAP: three letters with one turn
Choose Z at row 5, column 5 to begin ZAP. Move up to A at row 4, column 5, then left to P at row 4, column 4. Read the three selected letters as Z, A, P. There are two moves and one change of direction: a single upward step followed by a single leftward step. Stop at that P; this is the three-letter slot.
The opening Z sits in a corner and has only one open orthogonal neighbor, so check that first upward move before continuing. Once you reach A, the leftward step completes the required length. The finishing P has three open orthogonal neighbors, but you have already spelled the whole word. Count these as three distinct cells, leaving 18 for the other three answers, and check this finished path before comparing the next slot.