The best and most correct answer among the choices provided by your question is the fourth choice or letter D. Natural run-off from mountain ranges <span>is thought to be most responsible for the salinity of the oceans.
</span>After years and years of river inflow and evaporation, the salt<span> content of the lake water built up to the present levels. The same process made the seas </span>salty<span>. Rivers carry dissolved salts to the </span>ocean<span>. Water evaporates from the </span>oceans<span> to fall again as rain and to feed the rivers, but the salts remain in the </span>ocean<span>.</span>
Heating a hydrate leads to an endothermic reaction that produces a residue known as the anhydrous compound. This compound is different in structure, texture and even color in some cases, from its parent hydrate.
