challenge: Which of the following best describes the density of the heartwood of Eucalyptus guilfoylei?
  
  A. Roughly 1350 kg/m3 when air-dried
  B. Around 1250 kg/m3 when air-dried
  C. About 1185 kg/m3 when air-dried
  D. Approximately 1050 kg/m3 when air-dried
  Answer: 