Evidence of a Secular Trend Can Be Found in the Fact

Evidence of a secular trend can be found in the fact that

A) over the last 100 years more and more adolescents have enrolled and graduated from high school.
B) over the last 100 years people have developed a healthier diet.
C) over the last 100 years people have attained their adult height at earlier ages.
D) over the past 50 years, there has been a decline in the amount of exercise in an adolescent's life.