The correct answer is (a) driving.
The pressence of undesirable substances in air is called as air pollution. There are many human activities that contribute to air pollution. The biggest contributor is driving. The pollutants that comes out of the car are carbon dioxide, carbon monoxide. They also release hydrocarbon and nitrogen oxides which when combines in sunlight becomes ozone. Air pollutants emitted by cars and other automobiles increases the level of harmful gases which to severe health problems such as heart disease, asthma, irritation in eyes.
Animals have many advantages. But plants can make food anywhere there is sunlight/ultraviolet rays. So no need to hunt unless you're a Venus Flytrap. So plant cells can sustain themselves easier to a degree. As with many things in biology, it all comes down the the circumstances.
It begins producing acids and converting glucose instead of energy and the anaerobic exercise takes over then the power output drops and fatigue is getting in