challenge: When was the topographic survey conducted that mapped the location of Rongel reef?
  
  A. 8 December 1994 to 8 February 1995
  B. 8 December 1995 to 8 February 1996
  C. 8 December 1996 to 8 February 1997
  D. 8 December 1997 to 8 February 1998
  Answer: 