Question: What is the date of birth of Sönke Rothenberger's mother?
Sentence (from "Gonnelien Rothenberger"): She is married to German equestrian Sven Rothenberger, with whom she won the silver medal in the Team Dressage Event at the 1996 Summer Olympics in Atlanta, Georgia for Holland, alongside Anky van Grunsven and Tineke Bartels.
Relevant evidence: No