Option B: high pressure and low temperature
A gas is more soluble under high pressure and low temperature conditions.
On increasing temperature of a gas, its kinetic energy increases. The increase in kinetic energy increases the motion of particles of gas this causes most of the gaseous particles to escape from the gas phase. Thus, less particles are available to dissolve in liquid and solubility decreases.
The effect of pressure on solubility of gas can be explained with the help of Henry's law. According to the law, at constant temperature, solubility of gas and partial pressure of gas are related to each other as follows:
Here, p is the partial pressure of the gas, 
is Henry's law constant, and
c is the concentrate of the gas.
According to above relation, concentration of gas decreases on decreasing partial pressure. Thus, on increasing pressure, concentration of gas increases this increases the solubility of gas in liquid.
Therefore, solubility of gas is greatest at high pressure and low temperature.
