Several statements about chromosomes are given. 1. A chromosome contains one long DNA molecule. 2. Chromosomes contain genes. 3. During cell division, meiosis keeps the chromosome number unchanged. 4. The usual human chromosome number is 46. Which of these statements is correct?
- A1, 2, 3 and 4
- B1, 2 and 4 only
- C2 and 3 only
- D3 and 4 only