单项选择题

M: What are you doing, Mary
W: I am cooking dinner.
M: Look! The Capital Building caught on fire today.
W: What How about the people in the building
M: More than 220 people were killed and the building was destroyed.
W: It must have taken the fire fighters a long time to put it out.
M: Yes, they spent about five hours putting it out. Hmm, what a strange smell!
W: Oh, I forget the food cooking on the fire!
M: Be quick! Turn the gas off. You should be careful next time, otherwise, you’d have our house on fire!

What are John and Mary talking about()

A. Cooking.
B. The Capital Building.
C. The fire of the Capital Building.