Answer: B
Step-by-step explanation: How do we find the local extrema? Let f be continuous on an open interval (a,b) that contains a critical x-value. 1) If f'(x) > 0 for all x on (a,c) and f'(x)<0 for all x on (c,b), then f(c) is a local maximum value. 2) If f'(x) < 0 for all x on (a,c) and f'(x)>0 for all x on (c,b), then f(c) is a local maximum value.