Four reagents are given below. 1 aqueous $\text{KCl}$ 2 dilute $\text{HCl}$ 3 liquid $\text{SOCl}_2$ 4 solid $\text{PCl}_5$. Which of these reagents, when added to ethanol, would quickly generate a gas that makes blue litmus turn red?
- A1 and 2
- B1 and 3
- C2 and 4
- D3 and 4