Simplify the following text for a Grade 8 native English-speaking person.
Original: Waterson retired from Parliament in 1922 , but four new Co-operative MPs were elected that same year , including A.V. Alexander , all of whom took the Labor whip .
Simplified: Waterson retired from Parliament in 1922 , but four new Co-operative MPs were elected that same year , including A.V. Alexander . All of them took the Labor whip .