Alveolar walls are thin to enable the quick passage of oxygen in and out of the lungs. The lungs works hand-in-hand with the heart and also is responsible in converting blood that's de-oxygenated into an oxygenated blood that is usable by the organ systems of the body. The alveolar walls are also designed to have thin membranes so that it can expand and constrict quickly allowing us to breather properly.
I think the answer is b not too sure though
C. Color of leaves
If the question goes like this: Which best describes plant classification? <span>
A. Nonvascular plants are grouped into seedless and seeded plants. </span><span>
B. Seedless plants are grouped into gymnosperms and angiosperms.</span> <span>
C. Gymnosperms are grouped into monocots and dicots. </span><span>
D. Angiosperms are grouped into monocots and dicots.</span> <span>
The best answer will be letter D. Angiosperms are grouped into monocots and dicots.</span><span> Botanists grouped or classified together according to its characteristics. </span>
Ball and Socket Joint
This type of joint allows for a wide range of rotation and movement. The shoulder and hip are ball and socket joints.
