Complex sentence: Petra Karin Kelly (29 November 1947, Günzburg, Bavaria--1 October 1992), politician and activist, was instrumental in founding the German Green Party, the first Green party to rise to prominence worldwide.
Split into simpler sentences: Petra Karin Kelly (29 November 1947, Günzburg, Bavaria--1 October 1992) was a German politician and activist. She was instrumental in founding the German Green Party, the first Green party to rise to prominence worldwide.