When you are in school, almost any Subject seems a potential area for a good job.

what correction should be made in this sentence?

1)replace you are with one is
2)remove the comma after school
3)change Subject to subject
4)insert a comma after area
5)no correction necessary

And you think it's ... ?

i think it's number 5

The correction that should be made in this sentence is:

2) Remove the comma after "school".

The corrected sentence would be:
"When you are in school almost any subject seems a potential area for a good job."