Ecology takes into account only

Assertion $(A):$ A person goes to high altitude and experiences 'altitude sickness' with symptoms like breathing difficulty and heart palpitations.

Reason $(R):$ Due to low atmospheric pressure at high altitude, the body does not get sufficient oxygen.

In the light of the above statements, choose the correct answer from the options given below.

Thick cuticle, sunken and scotoactive stomata, $CAM$ photosynthesis and conversion of leaves into spines are some of the important characters of

Halophytes are

Smaller animals tend to lose body heat very fast as compared to larger animals because they have