Mark the letter A, B, C, or D to indicate the underlined part that needs correction in each of the following questions

VX. Mark the letter A, B, C, or D to indicate the underlined part that needs correction in each of the following questions.
1. The annual increase in the world's population has peaked at about 88 million in the late 1980s.
                        A                                 B                        C                      D
2. Overpopulation is one of the main factors that leads to poor, illiteracy, and social evils.
                A                              B                                           C         D
3. The teacher said that about 10 children need special help in reading skills.
                         A              B                        C                       D
4. Youth Newspaper lately donated book collections to two mountainous schools in northern Viet Nam.
                                           A                                       B                   C                              D