“Honors Physics is almost always the predecessor to Physics C in my experience. What else do you think would be needed?”
In most schools, Honors Physics is a step down from AP Physics 1, although I guess technically AP Physics 1 IS Honors Physics in schools that only offer choices of AP or CP. Our high school requires AP Physics 1 & 2 as prerequisites to C (though I realize the College Board says 1 is sufficient - but even just AP P1 could cover more than honors level, if the two are differentiated). Physics 1 (in our school) is primarily devoted to Mechanics, which is only the first half of the year of C. They have found that without 2, the kids struggle with E&M.