​The chemical reaction in which two reactants exchange their ions to form two new compounds is known as:​

Correct option is B

The correct answer is (B) double displacement reaction.

The chemical reaction in which two reactants exchange their ions to form two new compounds is called a double displacement reaction. It is also known as a metathesis reaction. 

Explanation:

• In a double displacement reaction, the positive ions (cations) and negative ions (anions) of the two reactants switch places. 
• The ions are exchanged because they are more attracted to the oppositely charged ions of the other reactant. 
• The driving force in these reactions is often the formation of a precipitate, a gas, or water.