I would say B because c and d would decrease competition and a would do the same, or just kill the ecosystem.
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Answer:
D
Explanation:
Organic compounds are chemical compounds which usually contains one or more atoms of carbon, hydrogen, oxygen and sometimes nitrogen or sulphur. Carbon and hydrogen are the main element that is contained in most organic compounds.
Option A is wrong because calcium phosphate is not an organic compound, although all the other compounds in the option are organic compounds.
Option B is wrong because calcium chloride is not an organic compound
Option C is wrong also as calcium sulphate is not an organic compound
Option D is correct as all are organic compounds
Answer:

Explanation:
You look at the type of atom and their electronegativity difference.
If ΔEN <1.6, covalent; if ΔEN >1.6, ionic
Ar/Xe: Noble gases; no reaction
F/Cs: Non-metal + metal; ΔEN = |3.98 – 0.79| = 3.19; Ionic
N/Br: Two nonmetals; ΔEN = |3.04 - 2.98| = 0.
The acronym is RNA. Ribo Nucleic Acid