No system is closed off by it surroundings.
Answer:
Obtain a immunization before flu season begins
Explanation:
The question asks for prevention and the other answers sTate what to do when you already have it.
B.Sometimes true,As you sometimes to need to learn on the alternative provided in getting a solution that is factual
The period during which the presence of stromatolites decline is the Proterzoic period. Stromatolites are widely distributed sedimentary structures consisting of laminated carbonate or silicate rocks, produced over geologic time by the trapping, binding, or the precipitating of sediment by groups of microorganisms, primarily cyanobacteria.
