Shelly's baby is 12 months old and is not walking yet.What should you say to her parents?

A) "Ninety percent of babies walk by the time they are 12 months old.Perhaps you should have the pediatrician check on her motor-skill development."
B) "Perhaps her fine motor skills are behind schedule."
C) "This is perfectly normal.While 50 percent of babies walk shortly after they are 12 months old,many don't walk until they are 15 months old."
D) "Don't worry about it! Only 25 percent of babies walk by the time they are 12 months old."