What is a whole step below D flat​

I believe it's C.

Explanation: The next note down from Db is C. The next note up from Db is D. Or put another way, D is 1 half-tone / semitone higher than Db. I'm not really sure if ur asking a basic music theory type of question or if ur asking a question for the instrument ur playing, but I hope this helps ^-^.

changeable lenses of different focal lengths allow light to enter the camera, which then forms the image on light-sensitive film" is the one among the following statements about working principle behind a basic still camera is true.