The answer is A. When two species use the same resources, this leads to competition between both species. In competition, one of the species must survive and the other must die.
Plants don't need salt water. It'll eventually die.
The heat energy is used to
move molecules further apart from each others.
When heat is applied, several phases of change occur , this is also known as a change of state. For example, when heating a liquid to make it a gas, also known as evaporation, you are making the spaces between the molecules even bigger because of the heat it suffered.