Consider the given two statements:
| I. | Sex chromosomes in male mammals also undergo synapsis in meiosis I |
| II. | Sex chromosomes are homologous chromosomes |
| 1. | Both I and II are correct and II explains I |
| 2. | Both I and are correct but II does not explain I |
| 3. | I is correct and II is incorrect |
| 4. | Both I and II are incorrect |