There is one mistake in each of the following sentences

V. There is one mistake in each of the following sentences. Find the mistake
and write your answer A, B, C or D. (1 point)
1. Preserving natural resources mean reserving them for our future.
       A                                            B            C                 D
2. Your brother hardly goes to work by bus, doesn’t he?
               A                    B                  C                 D
3. The water and land around the chemical factory are serious polluted.
          A                           B                                                 C             D
4. Many kinds of tigers are at danger now.
       A               B                 C                D
5. There is only one of her books which I have not read.
                     A          B                     C         D