Final answer:
The correct answer is option C. In Drosophila (fruit flies), dosage compensation is achieved by inactivating the paternally derived X chromosome in all somatic cells, whereas, in mammals like humans, mice, and cats, the inactivated X chromosome (Barr body) can be either maternally or paternally derived and occurs randomly.
Step-by-step explanation:
The species that achieves dosage compensation by inactivating the paternally derived X chromosome in all somatic cells is Drosophila (fruit flies). In humans and other mammals such as mice and cats, the process of X inactivation is random, meaning either the maternally or paternally derived X chromosome can be inactivated in each cell.
This process of X inactivation is crucial for dosage compensation, which ensures that females, with two X chromosomes, do not have double the amount of X chromosome gene products compared to males, who have only one X chromosome.
In mammals, the inactivation of one X chromosome in female mammals is observed during early embryonic development, resulting in the formation of a structure known as the Barr body.
All descendent cells from the initial cell with the inactivated X chromosome will have the same inactivated X. This mechanism is beautifully illustrated in tortoiseshell cats, where females exhibit a variegated coat pattern due to the random inactivation of X chromosomes carrying different coat color genes.
Contrary to this randomness seen in mammals, in fruit flies, the paternal X chromosome is always the one that gets inactivated. Consequently, Drosophila compensates for the difference in X chromosome dosage between males and females by this species-specific mechanism of dosage compensation.