Final answer:
Evidence for the Lyon hypothesis includes the presence of Barr bodies, random X chromosome inactivation in females, and dosage compensation in organisms with multiple X chromosomes.
Step-by-step explanation:
The evidence supporting the Lyon hypothesis of X inactivation includes:
- Presence of Barr bodies in cells with more than one X chromosome, which are the condensed, inactive X chromosomes visible in the nuclei of female cells.
- Random inactivation of one X chromosome in females during early development, ensuring that all cells derived from that cell have the same inactive X chromosome.
- The dosage compensation observed in organisms with multiple X chromosomes, where females compensate for their double genetic dose.
Option D, the expression of both X chromosomes in all cells, is not evidence supporting the Lyon hypothesis, as this would contradict the principle of X inactivation.