Refer to the Figure Below

Refer to the figure below.
Based on this figure, which conclusion is correct?

A) In many Western countries, puberty for both boys and girls is occurring at an earlier age than in the past.
B) Exposure to human-made chemicals is accelerating menarche in Western countries.
C) In many Western countries, girls are beginning their periods at an earlier age than in the past.
D) Boys tend to reach puberty at an earlier age than girls in most Western countries.