csc by default adds links to a bunch of assemblies. Look at csc.rsp in the same directory as csc.exe (for example, c: \ Windows \ Microsoft.NET \ Framework \ v3.5) to find out what is referenced by default.
You can specify your own answer file using @ as follows:
csc @ answers.txt Foo.cs Bar.cs
(This is not very useful, admittedly ...)
You can also prevent the use of the default answer file with /noconfig .
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