SQL Project not showing C# in the SQLCLR property

I am trying to create a SQL Server Project in SSDT but in the properties I can't see C# in the language dropdown. When I open a previously created SQL Project I can see the C# option. What do I need to do to create a SQL Project having C# language?

Software Versions installed on the system-

Microsoft Visual Studio 2013 Shell (Integrated)
Version 12.0.21005.1 REL
Microsoft .NET Framework
Version 4.8.04084

Installed Version: IDE Standard

Common Azure Tools   1.6
Provides common services for use by Azure Mobile Services and Microsoft Azure Tools.

SQL Server Analysis Services   
Microsoft SQL Server Analysis Services Designer 
Version 12.0.5000.0

SQL Server Data Tools   12.0.61021.0
Microsoft SQL Server Data Tools

SQL Server Integration Services   
Microsoft SQL Server Integration Services Designer
Version 12.0.2430.0

SQL Server Reporting Services   
Microsoft SQL Server Reporting Services Designers 
Version 12.0.2430.0

Windows Installer XML Toolset   3.10.2.2516
Windows Installer XML Toolset version 3.10.2.2516

Steps to create the SQL Project and reproduce the issue -

1. Open Visual Studio
2. Click on File -> New -> Project -> Template – SQL Server -> SQL Server Database Project.
3. Give the Name and select the location of solution.
4. Database project will be created.
5. Go to Solution Explorer -> Right click on Solution -> Properties.
6. Click on SQLCLR. Click on the Language drop down. Here I should see the C# option but it is missing.

What should I do to get the C# option in language?