What general trend applies to solubility? (a) Temperature is not related to solubility.
(b) As temperature goes up, solubility goes down.
(c) As solubility goes up, temperature goes down.
(d) As temperature goes up, solubility goes up.

Basically, solubility increases with temperature. It is the case for most of the solvents. The situation is though different for gases. With increase of the temperature they became less soluble in each other and in water, but more soluble in organic solvents.

a. energy is absorbed in the reaction.

if in a given reaction the energy of products is greater than the energy of reactants it means that reaction is endothermic and during the reaction, the energy is absorbed by reactants. in an endothermic reaction, the products have more stored chemical energy than the reactants. and in this reaction the reactants are more stable than products before the compounds with less energy are always more stable.