Answer:
The correct answer is - d. single replacement or displacement.
Step-by-step explanation:
The displacement or replacement reaction is the reaction in which the less reactive molecule or element is replaced by the more reactive element or molecule in the reaction. If there is only one replacement occurs its termed as a replacement or single replacement reaction.
In this case, if chlorine gas passes through the water solution of KI (potassium iodide), solid iodine and KCl are produced by the displacement or replacement reaction. Here iodine is less reactive so replaced by the more reactive chlorine.
2KI(aq)+Cl2 (g)→2KCl(aq)+I2 (s)