A 13-year-old comes to your office expressing concern about his height. He had first seen you a year prior for his routine checkup and a preparticipation sports physical for soccer (see growth curve). Now in the eighth grade, all of his friends are taller than he is, and he is at a disadvantage on the soccer field playing against much larger boys. After obtaining height information from his parents shown here, you order a skeletal bone age radiograph. Which of the following results would allow you to assure him of an excellent prognosis for normal adult height?
a) Skeletal age 12 years
b) Skeletal age 14 years
c) Skeletal age 16 years
d) Skeletal age 18 years