Calculus C

The College Board, the organization which develops and administers the AP exams, does not offer a "C-only" exam.  Their website doesn't state it outright, but, generally, depending on the college, the AB exam covers the first semester of college Calculus (Calculus I) and the BC exam covers the first two semesters of college Calculus (Calculus I and Calculus II).

You may want to CHECK whether the Physics course requires that you pass the BC exam before taking the Physics course.  IF YOU TOOK THE AB EXAM THIS YEAR, YOU CANNOT ALSO TAKE THE BC EXAM THIS YEAR.  Be sure that you know the requirements before you decided how to proceed.  You may want to spend your time and effort on something else this summer if you don't have an opportunity to take the exam.

The first five units covered in Calculus BC are identical to the first five units covered in Calculus AB.  You can possibly skip these, if you feel confident, or use them as a refresher.

Calculus BC includes additional material in units 6 - 8 and has two additional units that are not included in Calculus AB.  If you did well in AB, it may be sufficient for you to cover the additional materials.

All of that said, if the Physics course has its own "test-out" exam or if you are allowed to take the Physics course based on study alone and you do study the BC material, be sure to take the BC exam next year and get the college credit you deserve.