I believe it is 4)Shearing teeth (Carnassial teeth)
Amniotic egg are for reptiles
Fur are for marsupials, and dogs
Retractable claws are are cats
Shearing teeth are for carnivores
I believe the answer is either 1. Amniotic egg, or 3. Retractable claws
I hope this helps you! uwu
The answer is The Doppler Effect. It is named after the Austrian physicist Christian Doppler, who described the phenomenon in 1842.