Carmen has a sample of matter. It is clear and smells sour. The sample is also thick but it flows when poured. Which is the best conclusion about Carmen's sample?

liquid

Explanation:

In the given context, the sample as collected by Carmen is clear  and the sample has a sour smell. It is also mentioned that the sample is thick sample and when the sample is poured on a surface it begins to flow.

Such a sample would be a liquid sample because anything that flows is a liquid. The liquid sample has a high viscosity since it is thick.