Somebody Has Murdered a Dark-Haired Pre-Pubescent Girl in the Area

Somebody has murdered a dark-haired pre-pubescent girl in the area last year and left her mutilated body near the train tracks. This year, another dark-haired girl of about the same age was murdered and her body left near the train tracks in the same general area. Based on what you have learned from the textbook, can it be a serial killer's job?

A) Yes because there are enough similarities between the two cases.
B) Not conclusive because there are fewer than three cases with similarities.
C) Only if there is matching DNA evidence from the scenes of both crimes.
D) It must be either a serial killer or a mass murderer.