Answer:
The answer to this question is given below in the explanation section.
Step-by-step explanation:
The correct option for this question is the file extension. Because, by knowing the file extension, you can easily understand and know what the file is. If Evan checking out some groovy music files then he will definitely look at the file format to know that is it the music file or not.
Other options are not correct because:
messaging app function is to send the message, receive and store the message while hardware does not have any relation to identifying the music file and system software is an example of an operating system that also does not help the Evan for looking at music file on the laptop.