challenge: What is the primary question raised by Helge Tverberg in 1979 regarding geometric separators?
  
  A. What is the smallest number n(k,l) for two positive integers k, l?
  B. What is the median number n(k,l) for two positive integers k, l?
  C. What is the largest number n(k,l) for two positive integers k, l?
  D. What is the average number n(k,l) for two positive integers k, l?
  Answer: 