Valerie contracts with Esteban, who agrees to build a stone retaining wall and drain on her property. The wall and drain are necessary to prevent rapid erosion of her land, because of a fast-flowing creek. If Esteban breaches the contract, Valerie is under a legal obligation to

Mitigate her damages

Explanation:

A breach of contract involves the violation of any part of a signed agreement between two parties. For example, when a tenant destroys a property, he/ she has violated the contract with the house owner.

When there is a breach of contract, one of the two parties normally suffers damages, and he/she has a legal obligation to sue for mitigating damages. This minimizes the effect that the contract breach might have caused the person.  

Valerie contracts Esteban for a project capable of destroying her land if not done properly and quickly. A breach of contract leads to the project been abandoned and if damages are done on the land, Valerie is under a legal obligation to mitigate her damages through the court.

use this site

it is due to the halo effect as the impression of the boy created earlier.on the mind of the principle affected his decision