challenge: What is known about Mino di Graziano's work in Siena?
  
  A. He designed the architecture of the Palazzo Pubblico of Siena
  B. He painted frescoes in the Sala del Consiglio of the Palazzo Pubblico of Siena
  C. He painted frescoes in the Siena Cathedral
  D. He sculpted statues for the Palazzo Pubblico of Siena
  Answer: 