Which of the Following Was Part of Luther's Mature Theology

Which of the following was part of Luther's mature theology?

A) that justification may be achieved by faith alone
B) that the Bible is the sole source of religious authority
C) that the seven sacraments were the only means of attaining salvation
D) the validity of baptism and the Eucharist
E) both that justification may be achieved by faith alone and the validity of baptism and the Eucharist