challenge: What event in 1925 marked the beginning of a new era in Iran, leading to the rise of a Pan-Iranist movement?
  
  A. The overthrow of the Pahlavi dynasty
  B. The strengthening of the Shia clergy's power
  C. The rise of Reza Shah Pahlavi and the collapse of the Qajar dynasty
  D. The introduction of democratic reforms
  Answer: 