In a science experiment showing the splitting of water into Oxygen and hydrogen, two inverted test tubes of water were placed over the site of the reaction. (see the pic) How can you tell which one was catching the oxygen and which one was catching the hydrogen?

A. The hydrogen is a positive ion and will be located close to the negative terminal of the battery.

B. The oxygen is a negative ion which will be located next to the negative terminal of the battery.

C. There are 2 hydrogen atoms for every oxygen atom. The hydrogen will take up more space and is pushing the water lower in the test tube.

D. The hydrogen, being a smaller atom, will take up less space than the oxygen. It will push the water down less.