The average weight of a bacterium is approximately:

• A
  $0.2 \times 10^{-10} \text{ g}$
• B
  $0.2 \times 10^{-8} \text{ g}$
• C
  $0.2 \times 10^{-12} \text{ g}$
• D
  $0.2 \times 10^{-9} \text{ g}$