How long did it likely take for the Sergeant to die?

Choices:
A. He died after a few minutes
B. not enough information
C. He died a few days later
D. He died instantly
He died instantly
ROLAND NARROWED HIS EYES AND STARED UPWARD INTO THE DARKNESS, across the top of Mont Segur toward the Cathar fortress. Standing on a high walkway of planks behind the palisade of the crusaders' small wooden fort, he heard faraway voices and saw torches moving on the Cathar rampart.
The two men on watch with him that night, a sergeant from Champagne and a young man-at-arms from Brittany, were talking in low tones about the women to be had far below, at the foot of the mountain. They seemed not to see the activity about the Cathar stronghold on the upper peak of the mountaintop opposite their own fort. But Roland, knowing Diane was in the besieged fortress, could not take his eyes from it.
He knew he had to act soon. Each day the crusaders grew stronger and the Cathars weaker. Once the Cathar stronghold fell, the crusaders would slaughter all within, including Diane. The sergeant, chuckling, was offering his young companion a wineskin. The Breton never received it.
From behind the Cathar wall came the sound of a huge thump, as if a giant's fist had pounded Mont Segur. Roland recognized the sound, and fought panic as he thrust his arms out, trying to push the other two men toward the ladder. But there was no time for them to climb down to safety. The thump was the counter-weight of a stone-caster, and the whistling noise that followed fast upon it was the rock it had thrown.
A shape as big as a wine barrel blotted out the stars. The stone hit the parapet beside Roland, and the whole palisade shuddered. Roland caught a glimpse of the sergeant's horrified face and heard his scream as the boulder struck him, crushing him to the ground.