In a college having 600 science students, 450) students are doing Physics, 300 students are doing Mathematics and 400 students are doing Chemistory On These students 180 students are doing both Physics and Mathematics and 350 students are doing Physics and Chemistry 200 students are studying all three subjects. Then the number of students doing both Mathematics and Chenustry is

A

280

B

260

C

240

D

220