Valid C Expression

In C programming language, an expression is a combination of values, variables, operators, and functions that are evaluated to a single value. A valid C expression follows the syntax and rules of the C language.

Out of the given options, only option 'B' is a valid C expression.

Explanation

Let's understand why option 'B' is a valid C expression and why the other options are not valid.

a) int my_num = 100,000;
- This expression contains a comma (,) between 100 and 000, which is not allowed in C.
- In C, the comma operator is used to separate expressions, not to separate digits in a number.
- Therefore, this expression is not valid.

b) int my_num = 100000;
- This expression is valid because it follows the syntax and rules of C.
- It assigns the value 100000 to the variable 'my_num' of integer data type.

c) int my num = 1000;
- This expression contains a space between 'my' and 'num', which is not allowed in C.
- In C, variable names cannot contain spaces or special characters other than underscore (_).
- Therefore, this expression is not valid.

d) int $my_num = 10000;
- This expression starts with a special character '$', which is allowed in C but not recommended.
- In C, variable names should start with a letter or underscore, not a special character.
- Therefore, this expression is valid but not recommended.

Conclusion

Option 'B' is the only valid C expression out of the given options because it follows the syntax and rules of C. Other options contain syntax errors or violate the rules of C. It is important to write valid C expressions to avoid errors and unexpected behavior in the program.