At the beginning of the school year, 50 \% of all students in Mr. Wells’ math class answered “Yes” to the question “Do you love math”, and 50% answered “No.” At the end of the school year, 70 \% answered “Yes” and 30 \% answered “No.” Altogether, x \% of the students gave a different answer at the beginning and end of the school year. What is the difference between the maximum and the minimum possible values of x ?
Answer Choices
A. 0
B. 20
C. 40
D. 60
E. 80