Genetics

Step 1: Understand Barr body formation.
A Barr body is an inactivated X chromosome in female mammals, which occurs to balance the gene dosage between males and females.
Step 2: Analyze the options.
The Barr body is associated with the X chromosome and is found in females to prevent double expression of X-linked genes. Autosomes are non-sex chromosomes and are not involved in Barr body formation. The Y chromosome does not form a Barr body. Males do not have Barr bodies because they have only one X chromosome.
Conclusion: The correct answer is (B) X chromosome.