Question

which adaptation helps polar bears maintain a constant internal temperature (thermal homeostasis) in cold weather? three layers of fur blubber finding shade underground white skin

Explanation:

Polar bears have a thick layer of blubber under their skin. Blubber is a type of fat that acts as an insulator, helping to retain body - heat and maintain a constant internal temperature in cold arctic environments. While they have fur and white skin, the key adaptation for thermal homeostasis is blubber. Finding shade underground is not relevant as they live in icy areas with little underground shade.

Answer:

B. blubber