Which of these buildings is most likely to have indoor air pollution?

a school with leaks that allow water and heat to be wasted
an office building without a carbon monoxide detector
a tightly sealed house with an unvented water heater

If you have a stage 1 tumor, what would this indicate? that the tumor is confined to the organ where it started. that the tumor has grown into the surrounding tissue. that the tumor has invaded the lymph nodes. that the cancer has spread throughout the body.