[单选题]
A convex spherical mirror has a focal length of -20 cucx+kc6p ) vl5m. An objecji u.k v+u3m.lt is placed 10 cm inm.j+ 3uvk .liu front of the mirror on the mirror's axis. Where is the image located?
A. 20 cm behind the mirror
B. 20 cm in front of the mirror
C. 6.7 cm behind the mirror
D. 6.7 cm in front of the mirror
