It's actually A. Vertebrate have a hard out shell.
Answer:
Many organisms found on reefs produce chemical compounds that have been used in treatments for cardiovascular diseases, ulcers, leukemia, lymphoma, and skin cancer, and many more remain undiscovered.
Explanation:
hope this helps... but maybe not so sorry if im wrong :(
The right answer is D.
The density of a given population is calculated by dividing the number of inhabitants by the area expressed in km² (or in hectares).
Number of inhabitants ÷ area (in km²) = number of inhabitants / km²
A = 125000 organism/ 2.5 m2 = 50,000 organisms / m2
B = 13000 organisms / m2
C = 37500 organisms / m2
D = 200000 organisms / m2
