I know this has very little to do with astronomy, but I need the answer for The National Science-quiz here in Holland. Here's the question:

The weather is clear and sunny with a few clouds in the sky. Do these clouds float?

a. No, they don't float, but they fall very slowly, because water is heavier than air.

b. Yes, they float, because the specific gravity of the clouds is just a little less than that of air.

c. No, they rise slowly, because they expand heavily.

Anyone?

> Michiel <