If the salt created from the reaction of a strong acid and a weak base is added to a solution, it will cause the pH of the solution to decrease. This is because the salt will hydrolyze, meaning that it will react with water and release either H+ or OH- ions into the solution. In the case of a salt formed from a strong acid and a weak base, the salt will release H+ ions into the solution, making it more acidic and causing the pH to decrease. Therefore, the correct answer is A. The pH will decrease.