What're exact version of c# and .net unity use?

I know it’s depending on mono-framework.
And i know the page where .net compatible sheet wrote. But i need c# language version
Again and, mono version isn’t specified even that page

So, what’re exact version of those?(c#, .net or mono-framework)
And where can i find that on unity website?

There isn’t any exact .NET version. As of Unity 3.5, it uses Mono 2.6, which is sort of like .NET 3.5.

Please Use “Debug.Log(System.Environment.Version);” to get the .net version in unity.

Thanks-
Vipul Gandhi

I was looking for the answer and found it by myself, so I thought I would update the answer :

As of Unity 4.3, MonoDevelop 4.0.1 is used, which uses .NET 4.0

@bang2ni , as of version 2017.1, it can use up to C#6 and .NET 4.6 using the experimental mode. Otherwise, it uses .NET 3.5.

What’s new in 2017.1

I don’t even know for sure what versions I use…I download and use the latest versions (not the beta versions) of Unity and the Microsoft Visual Studio (which includes C#) and that is it. Whatever that gives me is what I use…I’ve found that to be fine for a casual user such as myself…although needs vary from user to user.