Final answer:
The option that is not a Java primitive type is 'real'. Java uses 'double' and 'float' for floating-point numbers, and 'real' is not a keyword or data type in Java.
Step-by-step explanation:
The question asks which of the following is not a Java primitive type: a. real, b. byte, c. char, d. double. In Java, the primitive types are the most basic data types and they directly contain values. The types byte, char, and double are among the eight primitive types that Java supports. The correct answer is option a. real. This is not a primitive data type in Java. Instead, Java uses double or float to represent floating-point numbers.