challenge: In weightlifting at the 1956 Summer Olympics, what was the rule regarding changing weights between attempts?
  
  A. Minimum increase of 5 kg between second and third attempts
  B. Minimum increase of 5 kg between first and second attempts
  C. Minimum increase of 2.5 kg between first and second attempts
  D. Minimum increase of 2.5 kg between second and third attempts
  Answer: 