What is the amount of light that passes through the lens and reaches the digital sensor called?

Answer the question in the image! i just need 4s answer but is 3 is wrong correct me uwu

Which sout american country has the highest population density

Ineed this to be answered fast and you i would appreciate it1. what benefits are there to using an online filter app? 2. of the apps you researched, which would you choose to edit your own photos? why would you choose this app over the other ones? 3. if you could choose between using the camera accessory filters that connect to your camera or the photo editing app filters, which would you choose and why?