What is the most significant challenge for organisms that live in estuaries? O A. Changing nutrient levels
O B. Changing water temperatures
O C. Changing water depth
O D. Changing water salinity
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Nitrogen-14 and nitrogen-15 are isotopes of the same element. how do these two isotopes differ? a. they have different numbers of nuclei. b. they have different numbers of protons. c. they have different numbers of neutrons. d. they have different numbers of electrons.