Which statement is true about variable names in Java?

Variable names in Java must adhere to specific rules and conventions. The statement that they can contain an underscore symbol ("_") is true. In Java, underscores are valid characters and are often used to separate words in a variable name, especially in cases where a developer opts for a naming style that enhances readability, such as snake_case.

For example, a variable name like my_variable is perfectly acceptable in Java due to the presence of the underscore. Other symbols, such as spaces or special characters like the percent sign (%), are not allowed in variable names, leading to syntax errors if used. While it is beneficial for variable names to be meaningful, there is no enforced requirement that they "make sense as a word"; this is more of a best practice for code readability rather than a strict rule in naming conventions.