For which of the following combinations, does the absorption operation become gas -film controlled?

• $P$. The solubility of gas in the liquid is very high
• $Q$. The solubility of gas in the liquid is very low
• $R$. The liquid-side mass transfer coefficient is much higher tan the gas-side mass transfer coefficient
• $S$. The liquid-side mass transfer coefficient is much lower than the gas-side mass transfer coefficient
1. $\text{P & Q}$
2. $\text{P &R}$
3. $\text{P & S}$
4. $\text{Q & R}$