Answer: B
Step-by-step explanation:
The Burn Tool in Photoshop is used regulate light exposure on an image by darkening areas where the brightness is too high. It works by increasing the exposure so that the image will be darker.
In option B, the light from the sun at the top of the picture is quit high and so can be regulated by the Burn tool. It can therefore be used as a "before" picture that will be adjusted.