Estuaries are important for all the following reasons EXCEPT... A. act as a nursery for many marine organisms
B. provide a habitat for many marine organisms.
C. are home to many phytoplankton, the bottom of the ocean food chain.
D. they prevent harmful wildlife from interacting with humans

the element that provides strength to the exoskeletons of clams and oysters is phosphorus. this is so because calcium carbonate is the main component in the shells.

explanation:

there really is life in the deepest part

the relative atomic mass of an element is the mass of one atom of that element, relative to 1/12th of the mass of a  1212c atom. to convert to an absolute mass in kg, it is necessary to multiply by  1.661×10−271.661×10−27.

the relative atomic mass is roughly equal to the number of neutrons, plus the number of protons, in the nucleus of the atom.

for elements with more than one stable isotope (different types of nucleus with different numbers of neutrons but the same number of protons), the quoted mass is usually the average mass, weighted by the relative abundance of the different isotopes.