Azure Pipelines Trying to Find Correct Environment Value repository checkout

what pipeline variable is this path? i'm hunting for the environment variable for this value i've tried $(Build.SourcesDirectory) and $(Agent.BuildDirectory) these all come up in C drive, is there a source of output for all the pipeline environment variables per run?

resources:
  repositories:
  - repository: self
    type: git
    ref: refs/heads/master
...
        steps:
        - checkout: self
...
        - task: PowerShell@2
          displayName: Display Build Dir
          inputs:
            targetType: 'inline'
            script: 'Write-Host "Build Directory Location: `"$(Agent.BuildDirectory)`""' 

        - task: NuGetCommand@2
          displayName: NuGet restore
          inputs:
            solution: '$(BuildParameters.solution)'
            selectOrConfig: config
            nugetConfigPath: '$(Agent.BuildDirectory)/src/tree0/nuget.config'

idk why but using NugetCommand@2 with 'restore' command on this windows agent uses back slashes \. There was no error informing me of this. I changed the slashes and it started working.

despite the docs stating elsewise, see: slash documentation pipeline and seeing no contrary info in the task documentation: path variable doc in NugetCommand@2 i was left to trial and error (not really, a coworker suggested it but I dismissed the advice after reading the docs, silly me)

the code WAS in C drive despite the output of the checkout task stating elsewise. How did I find this out. I ran a recursive directory output that showed all the files.