In Kernighan and Ritchie's "The C Programming Language" 1978 edition, there is no mention of how C got its name... and they designed it. They do mention that C was developed with concepts introduced by B (Ken Thompson) and BCPL (Martin Richards).
The C++ Programming Language text by Bjarne Stroustrup (The creator of C++) claims that "except for minor details, C++ is a superset of the C programming language."; "Earlier versions of the language, collectively know as 'C with Classes' have been in use since 1980." ; "The name C++ (pronounced "see plus plus") was coined by Rick Mascitti in the summer of 1983. The name signifies the evolutionary nature of the changes from C; '++' is the C increment operator. The slightly shorter name 'C+' is a syntax error; it has also been used as the name of an unrelated language. Connoisseurs of C semantics find C++ inferior to ++C. The language is not called D, because it is an extension of C, and it does not attempt to remedy problems by removing features. For yet another interpretation of the name C++, see the appendix of [Orwell, 1949 <ed -- presumably 1984, which I DON'T have on hand
>]."
Hopefully, this will put this topic to rest once and for all.