Barr body in mammals represents

1. all the heterochromatin in female cells
2. Y-chromosomes in somatic cells of male
3. all heterochromatin in male and female cells
4. one of the two X-chromosomes in somatic cells of females

A barr body is one of the X-chromosomes in somatic cells of females. If there are more X-chromosomes, then there will be more barr bodies.