Try to get to know the function of each part. The film is __
A.
in the back of the camera to hold the film. The film will sense the light and produce chemical reaction to develop the image.
B.
is the reflective device for the digital single lens camera. It is used to correct the reverse pictures on the focusing screen, so that operator can frame and focus correctly.
C.
the hole in the back of the camera that a photographer looks through to aim the camera.