challenge: According to Rousseau Flower, which of the following characteristics is used to define the Sactorthoceratidae family?
  
  A. Long camerae and slightly expanded siphuncle segments
  B. Coiled shell shape with a large body chamber
  C. Short camerae and rather short tubular septal necks
  D. Tubular siphuncle segments that are rapidly contracted at the septal foremina
  Answer: 