What are valid characters for naming a variable in JavaScript?

The choice indicating that letters, numbers, underscores, and dollar signs are valid characters for naming a variable in JavaScript is correct because these are the specific characters allowed by the JavaScript language specification for naming variables.

In JavaScript, a variable name must begin with a letter (a-z or A-Z), an underscore (_), or a dollar sign ($). After the first character, variable names can subsequently include any combination of letters, numbers (0-9), underscores, and dollar signs. This flexibility allows for a wide range of naming conventions, enabling developers to create meaningful variable names that can include descriptive prefixes or suffixes.

The other choices do not accurately represent the rules for variable naming in JavaScript. For example, restricting to letters and numbers excludes valid characters such as underscores and dollar signs. Saying any UTF-8 character would be misleading since there are specific rules that limit which characters can be used. Lastly, stating that only letters and dollar signs are valid would improperly exclude underscores, which are indeed allowed and commonly used in variable naming conventions.