Kristen is running a half marathon. By her tenth minute of running, her breathing rate has increased from her resting rate.
Which statement best describes how her tissues are responding to her running?
They need more oxygen to function, so gas exchange needs to decrease.
They need more oxygen to function, so gas exchange needs to increase.
They need more carbon dioxide to function, so gas exchange needs to increase.
They need more carbon dioxide to function, so gas exchange needs to decrease.