In the given diagram, circle A represents teachers who can teach Physics, circle B represents teachers who can teach Chemistry and circle C represents those who can teach Mathematics. Among the regions marked p, q, r ........ the one which represents teachers who can teach Physics and Mathematics but not Chemistry, is

Circle A is Physics and Circle C is Mathematics. The question asks for teachers who teach both Physics and Mathematics, which is the intersection of these two circles. However, we must exclude those who teach Chemistry (Circle B). The intersection of A and C includes regions 'u' and 'v'. Region 'v' is inside Circle B (includes Chemistry), while region 'u' is outside Circle B. Therefore, region 'u' represents teachers who teach Physics and Mathematics but not Chemistry.