This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous, Subject name: Pathology
Barr body is found in which phase of cell cycle? 
Select and explain. 
A. Interphase, B. Metaphase, C. G1 phase, D. Telophase
A: Interphase
Answer: A: Interphase 
Explanation: Barr body, or X chromatin The inactive X appears in the interphase nucleus as a darkly staining small mass adjacent to the nuclear membrane Molecular basis of X inactivation involves a unique gene called XIST, XIST codes for long noncoding RNA that is retained in the nucleus, where it "coats" the X chromosome that it is transcribed from and initiates a gene-silencing process by modification of chromatin and DNA methylation.