Student: A dragon has 100 heads. A soldier can cut off 15, 17, 20 or 5 heads, respectively with one blow of his sword. In each of these cases, 24, 2, 14, 17 new heads grow on its shoulders. If all heads are cut off, the dragon dies. Can the dragon ever die?
Options:
(A) 61
(B) 3
(C) 5
(D) 6
(E) 1.
Another student: Let's say, hmmm...

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
Here the difference in the cutoff heads and newly grown heads is 3. 100 is not divisible by 3. The dragon never die. Final answer: (B).