Question

which of the following is a valid variable name? ab - cd double num1

Explanation:

In programming, variable names can only contain letters, digits, and underscores and should not start with a digit. Also, they cannot use reserved keywords. "ab - cd" has a hyphen which is not allowed, "double" is a reserved keyword in many programming languages. "num1" follows the rules as it starts with a letter and contains only a letter and a digit.

Answer:

C. num1