All molecules are made up of:
a)hydrogen
b)minerals
c)atoms
d)gas

The only answer you can pick from that group is atoms, but it is a shaky answer. It's just that nothing else is appropriate. Hydrogen won't work C-Cl4 is a molecule. No hydrogen.

Minerals. Again CCl4 does not contain any minerals.

Gas: Doesn't work. Many things (perhaps even the majority of compounds) are not gaseous. For example NaCl is table salt. It's a solid

Choose C. Ions are what make me hesitant.

answer : one can design an experiment using a liquid and an additive that can be added to the liquid and observe the chemical changes in the reaction species.

one would need a beaker which is filled with a known amount of the liquid in which thermometer is placed to measure the temperature changes; after addition of the additive to the liquid solution one can note down the temperature change and find whether the reaction is endothermic or exothermic in nature. by subtracting the initial temperature value with the final temperature one can find the temperature changes.

various combinations of liquid and additive can be used. liquid in this case can be a known quantity of water and additives can be epsom salt or without epsom salt the experiment can be conducted to notice the changes. water and ice, hydrogen peroxide and dry yeast, vinegar and baking soda,etc.