manhattan gmat sentence correction guide 2007

[vscid]

In this guide on page 65, what is the difference between 3) and 4) ?

[esledge]

In the future, please post the text of the questions. I happen to have the guide at hand, so I will answer this time. Also, this belongs in the folder for our Strategy Guides, so I will move the thread.

#3. The student's work improved over the course of the semester, and they (the students) should be commended for it.

#4. The players' helmets need to be repainted so that they (the helmets) will be ready to be used at practice on Sunday.

Both sentences use "they" and have a possessive+noun subject. #3 is wrong because the antecent of "they" is a possessive modifier, not a noun. #4 is right because the antecedent of "they" is the possessed noun.