According to the cladogram shown, which two animal species shared the most recent common ancestor?
a. primates and crocodiles
b. birds and rodents
c. sharks and birds
d. birds and crocodiles

Birds and Crocodiles (Ans. D)

Explanation:  

Birds and Crocodiles shows most recent common ancestor because they are part of much larger group known as Archosauria (ruling lizards). When they both species divided from each others, they divided into 2 major evolutionary pathways:

The bird-line archosours , and the second one is crocodile-line archosours (which includes crocodilians and their ancestors).

So, Crocodiles are the closest living relatives of the birds and they sharing the most common ancestor.

tsd is temerature dependent sex determination.

tsd: it is a type of environmental sex determination in which the temperature experienced during embryonic/ larval development (ambient temperature for development) determine the sex of the offspring.

crocodile displays the tsd where the ambient temperature of the developing egg determines the individual's sex. for example in the american alligator's eggs, incubation at 33 ºc produces mostly males, while incubation at 30 ºc produces mostly females. so if the american alligator's egg will get the ambient temperature (33 degree celcius)during embryonic development from egg, the offspring will be male and same for the female sex determination.