Final answer:
The question is about understanding the meaning of a statement describing visibility in foggy conditions.
Step-by-step explanation:
The subject of this question is English because the question involves understanding the meaning of a statement that describes the visibility in foggy conditions.
The fog is so thick that you can't see 10 meters in front of you or the fog is so heavy that you can't see 10 meters ahead means that the fog is extremely dense and obstructs visibility to a distance of 10 meters. This is a common way of describing the intensity of fog and how it affects visibility.