In C, there are several primitive data types. The following are the common ones:
`int` is used to store integers.
`float` is used for storing single-precision floating-point numbers.
`char` is used for storing single characters.
However, `real` is not a valid data type in C. In C, for real numbers, the types `float` or `double` are used. The term `real` is commonly used in other languages (like Pascal), but not in C.
Thus, the correct answer is (c) real.