A: You hire an external contractor to do work (roofing, pouring concrete, creating a website, etc.), the contractor should have full autonomy (and liability) regarding how, when, and by whom the work is done--the contractor is responsible for the end result. A good (bad) example might be a language school--just the type of business that often operates in this grey area. A language school might 'hire' a teacher, technically an independent contractor, to do teaching work, yet nonetheless treat the teacher as an employee, specifying exact teaching times, methods, books, locations, etc., closely monitoring performance (as with an employee), and even integrating the person into an internal hierarchy (so the boss becomes a boss rather than a client). True autonomy (freedom from control) in this case would be the freedom to decide upon the times, locations, methods, materials, etc. and a dependence upon own's own independent expertise while performing the contracted duty.

C: The contractor (ideally) works for many companies (i.e. has many clients) and not just for you. Is the contractor (individual or company) independently established? When determining C, the authorities might look specifically at things like whether the contractor has an established business location, whether the contractor has employees, how much work the contractor does for any individual client, etc.