Which example best describes a process of how solar energy can be used to heat a home?

a.
sunlight hits copper tubes filled with water, that heats up and circulates to the house.

b.
sunlight causes a special chemical to boil and give off steam.

c.
sunlight turns a turbine that has been placed on top of a house.

d.
sunlight is reflected off of a rooftop causing the house to heat up.

Chronic obstructive pulmonary disease (copd) makes it difficult for the respiratory system to deliver oxygen to the lungs. the scientist wants to use a computer simulation to model how copd affects heart rate and respiratory rate during exercise. she will compare the results of the simulation to the results she gathered in her previous study. which of the following would be an appropriate dependent variable for the new study?