in that sence couldn't you say the same thing about C in its entirety since C++ is a subset of C?
What kind of nonsense is that?
Very brief history lesson:
C had many dialects. The original was written mostly by Dennis Ritchie at Bell labs from 1969-1973. The language was applied in several places and was customized and changed around. In 1979 there was a book attempting to standardize the language, as K&R C. The book was written by the two who contributed most to the language at that time.
The C++ language was one of the many dialects, called "C with Classes", used internally by AT&T. It was a dialect of the language.
Note that "C with Classes" was not a proper subset of K&R C. Even though they shared a common base and most of the trivial K&R C code could be made to compile with it, they were not absolutes. You could write K&R C programs that would not complile in C with Classes, and you could write C with Classes code that would not compile in K&R C.
Even back then, in 1980, neither language was a subset of the other.
In 1983 when the C language began to be standardized by ANSI, the "C with Classes" version was renamed C++. When C++ compilers hit the public in 1985 the language was a sibling of ANSI C, neither had a subset/superset or parent/child relationship. They were similar but distinct.
The two languages have a similar root from the 1970's, but neither language has ever been a subset of the other. They are similar, and many constructs are the same, but in no way is C a subset of C++, nor the other way around. The two languages have always been separate and distinct.