Answer : The correct option is, (a) Synthesis
Explanation :
Synthesis reaction : A chemical reaction where multiple substances or reactants combine to form a single product.
It is represented as,
![X+Y\rightarrow XY](https://tex.z-dn.net/?f=X%2BY%5Crightarrow%20XY)
Combustion reaction : A chemical reaction in which a hydrocarbon react with the oxygen to give product as carbon dioxide and water.
It is represented as,
![CH_4+2O_2\rightarrow CO_2+2H_2O](https://tex.z-dn.net/?f=CH_4%2B2O_2%5Crightarrow%20CO_2%2B2H_2O)
Single replacement reaction : A chemical reaction in which the more reactive element replace the less reactive element.
It is represented as,
![A+BC\rightarrow AC+B](https://tex.z-dn.net/?f=A%2BBC%5Crightarrow%20AC%2BB)
In this reaction, A is more reactive element and B is less reactive element.
Double replacement reaction : It is a type of chemical reaction where a positive cation and a negative anion of two reactants exchange places to form two new products.
It is represented as,
![XY+AB\rightarrow XB+AY](https://tex.z-dn.net/?f=XY%2BAB%5Crightarrow%20XB%2BAY)
(X and A are the cations, Y and B are the anions)
The given reaction is, ![Ca+Cl_2\rightarrow CaCl_2](https://tex.z-dn.net/?f=Ca%2BCl_2%5Crightarrow%20CaCl_2)
In this reaction, calcium combine with the chloride to form calcium chloride as a product.
Hence, the given type of reaction is a synthesis reaction.