For parents, a benefit of coeducation at both the elementary and high school levels is the assurance that as a child matures, their social skills improve as well.

1.the assurance that as a child matures, their

2.the assurance that as children mature, their

3.to assure that when a child matures, his or her

4.to assure that when children mature, their

5.assuring that as children mature, their

[spoiler]OA = 2
My doubt is their can refer to either the parents or the child ???[/spoiler]