I think it's D
again sorry if I'm wrong it just makes the most sense
The Alchemist concludes with Santiago at the end of his journey across the sea and sands, back to where he started, dreaming under a sycamore tree. That is until the last line of the novel, "I'm coming, Fatima..." (Epilogue.13); This line shows that Santiago's journey is not yet done and that he will continue to travel even after the end of the novel.
Its the past tense for tread. tread- to walk in a specific way