challenge: What was one possible explanation for the lack of detected organics by GC-MS in the Viking lander biological experiments?
  
  A. The GC-MS instrument was not sensitive enough to detect organic compounds
  B. The Martian soil lacked sufficient nutrients for microbial growth
  C. The oxidizing inventory of the H2O2-H2O solvent exceeded the reducing power of the organic compounds of the organisms
  D. The Martian atmosphere was too cold for microbial activity
  Answer: 