Read this: The city's largest private school by number of students is Temple University, followed by Drexel University. Along with the University of Pennsylvania, Temple University and Drexel University make up the city's major research universities. The city is also home to five schools of medicine: Drexel University College of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia College of Osteopathic Medicine, Temple University School of Medicine, and the Thomas Jefferson University. Hospitals, universities, and higher education research institutions in Philadelphia's four congressional districts received more than $252 million in National Institutes of Health grants in 2015.
Now answer this question, if there is an answer (If it cannot be answered, return "unanswerable"): What are the 3 research universities in the city?
University of Pennsylvania, Temple University and Drexel University