Final answer:
A legal identifier in programming starts with a letter or underscore and only contains letters, underscores, and digits. The legal identifier from the options provided is 'Five__Ten' because it adheres to these rules, unlike the other options which start with a digit, contain special characters, or are string literals.
Step-by-step explanation:
The question asks to identify which of the given options is a legal identifier in programming. A legal identifier is a name that you can use to identify a variable, function, class, module, or other objects in your code. Generally, a legal identifier starts with a letter (a-z or A-Z) or an underscore (_) followed by zero or more letters, underscores, and digits (0-9).5_and_10 is not a legal identifier because it starts with a digit.Five__Ten is a legal identifier because it starts with a letter and contains only letters and underscores.The identifier with only underscores (________) is also legal but not recommended for clarity.lovepotion#9 is not legal because it contains a '#', which is not allowed within an identifier.Finally, "hello world" is not legal because it contains spaces and is encapsulated in quotes, making it a string literal, not an identifier.Therefore, the answer is option 2) Five__Ten.
In computer programming and web development, a legal identifier is a name used to identify a variable, function, or other entity. A legal identifier must follow certain rules:It must start with either a letter or an underscore (_).It can contain letters, numbers, or underscores.It cannot contain any other special characters, such as spaces or punctuation marks.Based on these rules, the legal identifiers from the given options are:5_and_10lovepotion#9 is not a legal identifier because it contains the special character #.The other options are not legal identifiers because they either start with a number (Five__Ten), contain spaces (__), or contain special characters ("hello world").