The correct answer is A.
Hunger, chemical imbalance, and blood levels are all internal issues. Cat dander on the other hand is not something the body creates or and is something in the environment.
Thus, your answer is A.
<u>Answer:</u> The reactant ratio in the given chemical equation will be: 
<u>Explanation:</u>
Mole ratio is defined as the ratio of the amount of moles of two substances that are participating in a chemical reaction.
In the given chemical equation:

The reactants are Fe and
and the product is 
The mole ratio is basically the stoichiometric ratio of the chemical compounds taking part in a chemical reaction.
The mole ratio of reactants is stoichiometric ratio of Fe and
, which is:

Hence, the reactant ratio in the given chemical equation will be: 
Answer:Liquids expand for the same reason, but because the bonds between separate molecules are usually less tight they expand more than solids.
Explanation:Heat causes the molecules to move faster, (heat energy is converted to kinetic energy ) which means that the volume of a gas increases more than the volume of a solid or liquid.