Return unique values from large dataset

[AccountantGuy]

Hello,

Long time reader, first time poster.

I have a large dataset of relationships between "C Items" and "R Items". For a given "C Item" I would like to return each associated unique "R Item" only one time. Some "C Items" may have only one "R Item" and others may have fifty. I've included screenshots of a mock up of the data and the desired outcome I'm seeking to reach.

I imagine this is much easier than I'm making it but after going down a rabbit hole of countif's and index matching, its time to ask the experts. Any recommendations?
Thanks!

 

[Fluff]

How about in A5

=UNIQUE('Data File'!A2:A21)

and in B5 dragged down

=TRANSPOSE(UNIQUE(FILTER('Data File'!$B$2:$B$21,'Data File'!$A$2:$A$21=A5)))

 

[AccountantGuy]

You're a legend mate, been reading your responses for years.

As usual, this was the solution! Thank you for your help.

 

[Fluff]

You're welcome & thanks for the feedback.