*question number 75*/
Which one of the following is true for identifiers that begin with an underscore?
Choice 1
They are generally treated differently by preprocessors and compilers from other identifiers.
Choice 2
They are case-insensitive.
Choice 3
They are reserved for usage by standards committees, system implementers, and compiler engineers.
Choice 4
Applications programmers are encouraged to employ them in their own code in order to mark certain symbols for internal usage. Choice 5
They are deprecated by Standard C and are permitted only for backward compatibility with older C libraries.


Is the answer (1) ?