Which are the MOST dominant chemolithotrophs in pelagic waters?

Which are the MOST dominant chemolithotrophs in pelagic waters?
 
  A) ammonia-oxidizing Archaea
  B) ammonia-oxidizing Bacteria
  C) sulfate-reducing Bacteria
  D) Prochlorococcus

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Which bacterial genus is responsible for producing ferrous iron (Fe2+) in groundwater?
 
  A) Alteromonas
  B) Aquifex
  C) Geobacter
  D) Loktanella

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The chemical oxygen demand (COD) of a body of water is determined using a(n)
 
  A) microelectrode.
  B) oxygenator.
  C) spectrophotometer to determine the OD540nm.
  D) strong oxidizing agent.

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An organism living in the bottommost region of a body of water is described as being
 
  A) benthic.
  B) litoral.
  C) neritic.
  D) pelagic.

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Which is the CORRECT order of increasing size in soil particles?
 
  A) clay > sand > silt
  B) clay > silt > sand
  C) sand > clay > silt
  D) silt > clay > sand