What happens when peristalsis occurs in the digestive tract

 D) check if one element replaces another element in a compound.

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 double displacement reaction is one in which exchange of ions take place.

A neutralization is a chemical reaction in which an acid reacts with the bas to form salt and water.

A) check whether the products are salt and water- neutralization

B) check whether the reactants are an acid and a base: neutralization

C) check if the irons of two compounds exchange places: Double displacement

D) check if one element replaces another element in a compound: single replacement