Subject: mathqa
Question: a group of people participate in some curriculum , 30 of them practice yoga , 25 study cooking , 15 study weaving , 6 of them study cooking only , 8 of them study both the cooking and yoga , 7 of them participate all curriculums . how many people study both cooking and weaving ?
Option: 
A: 5
B: 1
C: 4
D: 3
Answer: C