Out of those options, I would go with Economics.
Your options seem a bit random though. Your opportunities in both the Sciences and the Arts will be limited. You only have one essay-based facilitating subject, and you'll only be able to go into a single field of science.
If you could, drop Psychology, pick up an essay-based facilitating subject, keep Maths, and take a Science subject that appeals to you. You'll have better access to both Science and Arts subjects.
You don't need Psychology A-level to do it at university. Whilst there are no specific subject requirements for Law, a number of universities advise students to take two essay-based facilitating subjects.