Step 1: Break down the clue.
The key words are a distance in front of the camera, and actors and the entire scene in focus. So we need a range of distance, not a single number and not a single point.
Step 2: Think about what a cinematographer controls.
A cameraperson uses aperture, focal length and subject distance to change how much of the scene is sharp. The name for the zone of sharpness that results is depth of field.
Step 3: Test each choice against the clue.
Focal length is a lens property in millimetres. Focus is a single setting for a subject. Area of focus is not an accepted technical term. None of them describes a zone of sharp distance.
Step 4: Choose.
Only depth of field describes a zone of sharpness, so option 1 is the answer.
Final Answer:
The correct term is depth of field, which is option 1.
\[ \boxed{\text{1}} \]