Which of the following is not a valid class declaration?
A. class building {} B. class Cost$ {} C. class 5MainSt {} D. class _Outside {}
C.
Class names follow the same requirements as other identifiers.
Underscores and dollar signs are allowed.
Numbers are allowed, but not as the first character of an identifier.
Option C is correct.
class names begin with an uppercase letter by convention, but this is not a requirement.