See if you know why that is the correct answer. Each question has a link to one page that will add more to this topic. You might also use the search engine for the site to find other pages that have the same information. Equivalent exposure means using a different shutter and aperture to make identical exposures. It is used to control depth and motion.
Shutter speed interprets action.
The most interesting part of our subject should be placed in the center of the photograph. It is sometimes ok to break a rule of composition . This is called artistic license. If you are photographing a dinosaur using a 500 mm lens is a good idea to keep you far away so you won't be squished. Use the Search Engine to find more pages.