How can you change the value for the username key in the loginInfo object to "GA-Staff"?

The option that states "loginInfo.username = 'GA-Staff';" is correct because it demonstrates a basic property assignment in JavaScript. In this syntax, the dot notation is being used to access the username property of the loginInfo object. By directly assigning the new value, "GA-Staff", to loginInfo.username, you're effectively updating the value associated with that key within the object.

This approach is straightforward and widely used in JavaScript to manipulate object properties, making it easy to read and write. Dot notation is typically preferred for its clarity when dealing with property names that are valid identifiers.

The other choices reflect different approaches or incorrect spellings. For instance, using square bracket notation as shown in one option is also a valid way to access and modify object properties, but it involves quoting the property name, which is unnecessary here. The option that implies using a method to set the property value is incorrect since standard JavaScript objects do not have a built-in setUsername method. Lastly, the option with the misspelling 'logingInfo' would result in an error as it refers to an undefined variable.