When using a film camera, what must you do to bring an object into focus?
a. move the lens toward or away from the film.
b. close the diaphragm.
c. adjust the speed of the shutter.
d. adjust the angle of the mirror.

a. move the lens toward or away from the film.

Explanation:

Lets discuss the function of different components of the camera

a). Lens : Lens position is set to focus the image on the film as we know that

here we know that position of lens can adjusted by changing the value of distance from object and that will help to focus the image on the film.

b).  diaphragm. = It is used to control the intensity of light to enter into the lens so that light is adjusted.

c). speed of the shutter = By changing the speed of shutter we can control the light entering into the lens which can control the brightness of picture

d) Angle of mirror : by adjusting the angle of mirror we can set the orientation of the image that is formed

the answer is f1 and d2 because if you put equal force on those two points the beam would balance trust me on this