Which of the following is the most likely reason for the trend shown in the graph of fluctuating indoor radon levels over the course of a year? Home windows are often closed during summer months, causing the levels of radon in the house to build up. A Barometric pressure changes from summer storms can cause radon levels to increase. B Radon levels tend to increase in the colder months because of the difference in temperature inside and outside the home, which creates a vacuum pulling radon into the home at a higher rate. C Increased levels of radon are linked to burning biomass indoors, which increases in winter months when more biomass is burned for cooking and heating.