Describe the use of namespaces when using C#

please answer do not image format and properly explanation.

Code to _develop software using a regular expression module to process the following phone numbers.you are to extract the area code,trunk, number, and optionally an extension for each number. You may use the regular expression module in the language of your choice, please note that we covered the syntax for Perl 5 which is imitated by python 3, javascript, C++, and C#. Java, too. 800-555-1212 800 555 1212 800.555.1212 (800) 555-1212 1-800-555-1212 800-555-1212-1234 800-555-1212x1234 800-555-1212ext. 1234 1-(800) 555.1212 #1234 Reporting: Demonstrate your results by outputting the extracted information for each input number. Your report should be one page and it should be include a discussion of your use of the regular expression module..

A header of a C-language function is: void recurs(int current_level, int max_level ) The keyword "void" here signifies