[E]OG-69，请指点！

excellent

69. Although she had signed a pledge of abstinence while being an adolescent, Frances Willard was 35 years old before she chose to become a temperance activist.
A.while being an adolescent
B.while in adolescence
C.at the time of her being adolescent
D.as being in adolescence
E.as an adolescent

答案是E。请问E是不是as she was an adolescent的省略形式？

halcyon

as 介词， ”作为“的意思。