Why is it best to avoid proofreading during the revision process?

Does anyone know the answer to the question?

Which statement best summarizes this excerpt from leo tolstoy's the death of ivan ilyich? and in imagination he began to recall the best moments of his pleasant life. but strange to say none of those best moments of his pleasant life now seemed at all what they had then seemed—none of them except the first recollections of childhood. there, in childhood, there had been something really pleasant with which it would be possible to live if it could return. but the child who had experienced that happiness existed no longer, it was like a reminiscence of somebody else.

Which sentence corrects the error in pronoun-antecedent agreement? new team members should pick up his or her jersey from the activities office. if a team member is unable to attend a practice, he or she must provide a doctor's note. if students wish to compete, he or she must maintain a grade point average above 2.5. students are not permitted to attend away games without the consent of her parents or guardians.