challenge: According to scholars, what is the widely accepted origin date of the Shaka era?
  
  A. The ascension of Indo-Scythian king Chashtana in 78 CE
  B. The beginning of the Satavahana dynasty
  C. The creation of the Indian national calendar
  D. The defeat of Śaka rulers by Satavahana king Shalivahana
  Answer: 