Detailed Instructions: In this task, you are given a context and four options. Each option is a suggested ending for the context. You should read the context and pick the best ending for the context. Please answer with "A", "B", "C", and "D".
Q: [header] How to use a light meter [title] Prepare your camera. [step] Go into the settings of your camera and set it to manual mode, if it isn't in that mode already. Set your camera to your preferred iso and aperture settings. <sep> (A) Find the switch that goes on the back of the camera but don't worry about manually pressing it. Right now use the focal control or opacity control. (B) Make sure that you are connected to a recording device for an iso service. [substeps] You will not know if the device will sound when it has been activated until you press the right arrow (below the camera logo on the top right corner of your device) or use the analog camera led to turn off the device. (C) You'll need to do some experimenting with both of these settings to find the ideal settings for the photo you're trying to get. [substeps] The iso setting determines your camera's sensitivity to light. (D) [substeps] These settings are usually located at the bottom of the camera's box. If you haven't taken a picture or two before, you can adjust them now by turning on switch zoom up, switch aperture down and transparent sensitivity mode.
A:
C