In this task, find the most appropriate number to replace the blank (indicated with _ ) and express it in words.
One example is below.
Q: A lion has _ legs.
A: four
Rationale: The most logical numeric answer in words is four.
Q: Snakes have either a three-or _ chambered heart.
A:

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
four