Final answer:
To increase solubility in a liquid-liquid extraction, the temperature can be increased to boost the solubility of solids and liquids, while increasing pressure is the method for enhancing the solubility of gaseous solutes per Henry's Law.
Step-by-step explanation:
In the context of liquid-liquid extraction, to increase solubility of a substance typically involves altering certain conditions. With regards to the choices presented in the question, increasing temperature generally increases the solubility of solids and liquids in a solvent. This is due to the fact that heating up a solvent gives the molecules more kinetic energy, which allows them to collide more forcefully and frequently with the solute particles, thereby increasing the dissolution rate. For gaseous solutes, however, solubility decreases with an increase in temperature, as explained by observing the gaseous solute's molecules tending to escape into the gas phase upon heating. Considering Henry's Law, which describes the proportional relationship between pressure and the solubility of a gas in a liquid, increasing pressure potentially increases solubility for gases. Therefore, of the options provided, increasing pressure (b) would typically increase the solubility of a gas in a liquid, and increasing temperature may increase the solubility of solid or liquid solutes.