"His mind was crowded with memories; memories of the knowledge that had come to them when they closed in on the struggling pig, knowledge that they had outwitted a living thing, imposed their will upon it, taken away its life like a long satisfying drink."
I believe the answer is D. Before, because Also and During would make it grammatically incorrect and if you consider the fact that they were able to, "see and hear the explosion," then Eventually would not fit because that makes it sound like it took a bit of time.
