Given a sentence and two mentions from the text (arguments), indicate a phrase (a verb or noun phrase) that describes the relationship between the provided arguments.

Sentence: 'For example , most people know Margaret Sanger as the founder of Planned Parenthood , but she also was a strong advocate of eugenics .', Argument/Subject 1: 'margaret sanger', Argument/Subject 2: 'plan parenthood'
be founder of