The parent content type specified by content type identifier ... does not exist

Problem: When I deploy a solution that automatically activates a feature I receive the following error "Error occurred in deployment step 'Activate Features': The parent content type specified by content type identifier 0x0120D520 does not exist.".
Initial Hypothesis: The feature being deployed relies on another feature being activated, in this case it is the 'Document Sets' site collection feature that is missing.
Resolution: Site Settings > Site Collection features > Document Sets (Activate)

More Info:
http://msdn.microsoft.com/en-us/library/aa543822.aspx