The answer is B.) Freezing of water
Answer: AgCl + Fe
Explanation:
A single replacement reaction is one in which a more reactive element displaces a less reactive element from its salt solution. Thus one element should be different from another element.
A general single displacement reaction can be represented as :

The blanced chemical reaction will be :

It has a double C=C bond so that means it's unsaturated, but it can also be a cyclic compound with only simple C-C bonds