Final answer:
D. At the bifurcation of the Trachea into 2 Bronchi. The carina is located at the bifurcation of the trachea into two bronchi in the lungs.
Step-by-step explanation:
The carina is located at the bifurcation of the trachea into two bronchi. When the trachea enters the lungs, it divides into the right and left primary bronchi at the carina. These bronchi further divide into smaller bronchi, bronchioles, and finally into alveoli, where gas exchange occurs.