GMAT关于Harrilet Tubman的那题问一下

After the Civil War contemporaries of Harriet Tubman's maintained that she has all of the qualities of a great leader coolness in the face of danger an excellent sense of strategy and an ability to plan in minute detail.

(A) Tubman's maintained that she has
(B) Tubman's maintained that she had
(C) Tubman's have maintained that she had
(D) Tubman maintained that she had
(E) Tubman had maintained that she has

答案是d

contemporaries of Harriet Tubman's 错是不是因为tubman是第三人称单数啊，咱们不是老说a friend of mine，是不是GMAT中这种表示是错的啊。