challenge: What was Tchoung Ta-chen's approach to teaching his students?
  
  A. To teach his students everything he could and emphasize hard training
  B. To hold back and only reveal secrets to select students
  C. To focus on the performance aspect of t'ai-chi ch'uan
  D. To prioritize the calisthenics exercise aspect of t'ai-chi ch'uan
  Answer: 