To answer this question, you need to understand the file extensions used in ASP.NET for different types of web pages.
Option A) .aspx - This option is incorrect because .aspx is the file extension for ASP.NET web forms pages.
Option B) .ascx - This option is incorrect because .ascx is the file extension for ASP.NET user control files.
Option C) .asmx - This option is correct because .asmx is the file extension for ASP.NET web service pages. Web service pages in ASP.NET are used to expose web services that can be consumed by other applications.
Option D) .ashx - This option is incorrect because .ashx is the file extension for ASP.NET generic handler files.
The correct answer is C) .asmx. This option is correct because .asmx is the file extension associated with web service pages in ASP.NET.