The correct answer to this question is C. Turn the fan on continually. Depending on where one is in the country, wintertime can be blistering cold. It can be hard to keep any home warm during this time, but with the fan on, the warmth from the heat will be rotating and spreading to each room.
Doing so will allow a homeowner to be able to use their basement or attic again, without facing freezing temperatures. Running the heat is another option, but that will be extremely costly. It may also make the rooms too hot. Running the fan is a more cost-friendly and effective option.
By keeping the fan on all the time, the heat in your home is rotated and colder spots will be come warmer and comfortable. Imagine being able to use your basement in the winter again. This holds true in the summer time too by taking the coolness out of the basement and circulating it throughout the house (and also getting rid of the damp smell in the basement too). The only thing to be concerned about is that most furnaces do not have a variable speed fan and can cost you well over $200 to run a year. (Newer ESC fan motors area variable speed and can cost as low as $20 to run for the entire year)