In season 9 of "The Office," Dwight learns that he is not the father of Angela Martin's baby. The child is named Phillip, after Angela's favorite cat, and Angela is married to Pennsylvania State Senator Robert Lipton when the baby is born.
Dwight suspects that Phillip is his son because he and Angela had a secret relationship around the time of the baby's conception. In season 8, he even takes a dirty diaper for DNA testing, but the result announced at the beginning of season 9 says that he is not the father.
The storyline becomes deliberately confusing because Angela later tells Dwight that Phillip is actually his biological son. The show implies that Dwight tested the wrong diaper, possibly belonging to Jim and Pam's similarly named baby, Phillip Halpert. Thus, the quiz answer refers to Angela, the character whose baby is at the center of the paternity plot.