Respuesta :
Sour
Sour is the best word from the excerpt to establish the tone of the passage. In the excerpt it is clear that the narrator does not feel good about throwing his grenade. He says "I did not hate the young man; I did not see him as the enemy..." However, the narrator "had already pulled the pin". He is about to throw the grenade at this person who he does not feel any animosity towards. This "sour" taste in his mouth shows his dislike for what he's about to do.