Generate a topic word for the given sentence. A topic word is usually the name of a person, place, animal, concept or object the sentence is focusing on.

ronald ross (13 may 1857 16 september 1932) was an english doctor.
ronald ross

rsgc1 is a massive young open star cluster in the milky way galaxy.
rsgc1

george church (born august 28, 1954) is an american molecular geneticist.
george church