Given the task definition, example input & output, solve the new input case.
Given a scientific question, generate a correct answer to it.
Example: Who proposed the theory of evolution by natural selection?
Output: darwin
This is a direct fact that Charles Darwin proposed the theory of evolution.

New input case for you: All solutions contain at least how many substances?
Output:

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
two