Increasing the physical demands on the body over time to improve abilities is known as a. reversibility b. increased intensity c. muscular strength d. progressive overload

Increasing the physical demands on the body over time to improve abilities is known as "progressive overload".

Progressive overload implies that you are persistently expanding the demands on your muscles so as to make gains in their quality, size and perseverance. The harder you work them, the more grounded you move toward becoming. It sounds evident I know, however for some individuals, its simple to dismiss it.  

There might be a load you struggle to lift at first. Following up to 14 days, you figure out how to lift it. Awesome. With progressive overload, it doesnt stop there. Add more load to drive your muscles considerably more, to lift greater loads. Its this basic idea that resistance preparing is based upon.

the answer to this is D. Progressive overload

looks like you are missing options or a image.

i agree d is most definitely correct!