challenge: What was the result of the 2011 census in relation to Tehran County?
  
  A. The cities of Bumahen and Pardis, and most of Siyahrud Rural District, were separated from the county to form Pardis County
  B. No changes were made to the county's boundaries
  C. The county was split into two smaller counties
  D. The county was merged with another county
  Answer: 