Do you know why C language has "_" (underline)?

The C language learns that variable names can only consist of letters, numbers, underscores, and can only start with letters or underscores.

When we learn English, we all learn the hyphen ("-"), which is mainly used to connect words. So why not C language directly

Use a hyphen instead of an underscore?

Specifically looked up, found the answer.

(from Https://en.wikipedia.org/wiki/Naming_convention_ (programming))

The original is because the "hyphen" and "minus" both use the same "-", C language has been used "-" to denote a minus sign, it can not be placed in the variable name

When the hyphen is used, it is replaced with an underscore.

The above mentioned Lisp language can be used "-", because according to the Lisp grammar rules can be judged "-" represents a minus or a hyphen.

Do you know why C language has "_" (underline)?