Correct option is C)
Barr body is an inactive X chromosome which becomes tightly coiled into heterochromatin in early embryogenesis. It is related to dosage compensation which is accomplished by the inactivation of one of the X chromosomes in females. This is done so that both males and females have only one functional X chromosome per cell because human males have only one X chromosome, whereas females have two and hence, twice the genes present on the X-chromosome. The number of Barr bodies is one less than the total number of X chromosomes. Hence, a female with 4 X-chromosomes (XXXX) will have 3 Barr bodies. Thus, option C is correct answer.