In a Survey of the Dining Preferences of 36 Dormitory

Multiple Choice

In a survey of the dining preferences of 36 dormitory students at the end of the spring semester, the following facts were discovered about Adam's Lunch AL, Pizza Tower PT, and the Dining Hall DH. ​
13 liked AL but not PT
1 liked AL only
21 liked AL
20 liked PT
25 liked DH
7 liked PT and AL but not DH
10 liked PT and DH
​
How many liked PT or DH?
​

A) 15
B) 16
C) 99
D) 6
E) 35