The only correct parse of that one that I could generate with the options available was: "Every member of a group was satisfied with that group's grade". Which isn't what they meant, I suspect -- they needed to provide either "his or her" or just "his" -- which is still correct per grammar if not PC these days.
(no subject)
(no subject)
Unless every member of the group was female, in which case "her" would fit, but they didn't specify!