Which of the following statements are so related that they cannot both be true nor can they both be false?
(A) All mammals are vertebrates.
(B) Some mammals are vertebrates.
(C) Some mammals are not vertebrates.
(D) No mammals are vertebrates.
Choose the correct answer from the options given below:
1
(A) and (B) Only
2
(B) and (D) Only
3
(C) and (D) Only
4
(A) and (D) Only