Some High Schools in the United States Are Beginning the School

Some high schools in the United States are beginning the school day later and ending it in the evening. What research regarding circadian rhythms caused these schools to change their start and end time?

A) Adolescents have a melatonin surge later in the day, causing them to have difficulties waking early and allowing them to stay up late.
B) Adolescents circadian rhythms cause them to feel more positively towards a school day that begins later.
C) Adolescents release thyroxin at high levels, causing them to need more morning sleep and a later bedtime.
D) Adolescents attendance rates improve if the commencement time is later in the day.