The answer is b. is under purifying selection
Endocrine signaling is hormone based signaling that travels through the blood stream. Many of the sensors and integrating sensors of the endocrine system are located in the brain. The brain barrier contributes to endocrine signalling, such that the brain barrier does not factor in with endocrine signalling. The answer is A
Answer:
Triassic Period (252 to 201 million years ago)
All continents during the Triassic Period were part of a single land mass called Pangaea. This meant that differences between animals or plants found in different areas were minor.
The climate was relatively hot and dry, and much of the land was covered with large deserts. Unlike today, there were no polar ice caps.
It was in this environment that the reptiles known as dinosaurs first evolved. Reptiles tend to flourish in hot climates because their skin is less porous than, for example, mammal skin, so it loses less water in the heat. Reptile kidneys are also better at conserving water.