Answer:
For a: The reaction is a double displacement reaction.
For b: The reaction is a combustion reaction.
For c: The reaction is a single displacement reaction.
For d: The reaction is a neutralization reaction.
Step-by-step explanation:
For the given equations:
Equation 1:

This reaction is an example of double displacement reaction because here exchange of ions takes place.
Equation 2:

This reaction is an example of combustion reaction because here hydrocarbon is reacting with oxygen gas to produce carbon dioxide gas and water molecule
Equation 3:

This reaction is an example of single displacement reaction because here more reactive element displaces a less reactive element.
Equation 4:

This reaction is an example of neutralization reaction because here a base reacts with an acid to produce a salt and water molecule