单选题 The table below shows the enrollment in various classes at a certain college.

class0	Number of Students
Bioloby	50
Physics	35
Calculus	40

Although no student is enrolled in all three classes, 15 are enrolled in both Biology and Physics, 10 are enrolled in both Biology and Calculus, and 12 are enrolled in both Physics and Calculus. How many different students are in the three classes?
A. 51
B. 88
C. 90
D. 125
E. 162

【正确答案】 B

【答案解析】To find the total number of students, you must separate them into nonoverlapping groups so that no one is counted twice. The students taking only Biology are the 50 students minus the 15 also taking Physics and the 10 also taking Calculus, so there are 25 students taking just Biology. Using this same method, the number of students taking just Physics is 35-15-12=8, and the number taking just Calculus is 40-10-12=18. The total number, then, is 25+8+18+10+15+12=88.