It really depends on the point of view or the angle from which u are judging the problem or the argument.
C++ can be used to write procedure oriented as well as Object oriented in an easy manner so from this point of view C is subset of C++.
I know there is also object oriented C but thats not very widely used as ppl very much prefer to migrate to C++ for OOP rather than useing Objective C.
Does C support Operator Overloading, Funciton overloading, Function overriding, Virtual funcitions, etc. etc.
I hope u get the drift.