120. The Parthenon was a church from 1204 until 1456, when LACE>AthensLACE> was taken by General Mohammed the Conqueror, the Turkish sultan, who established a mosque in the building and used the Acropolis as a fortress.

(A) who established a mosque in the building and used the Acropolis as

(B) who, establishing a mosque in the building, used the Acropolis like

(C) who, when he had established a mosque in the building, used the Acropolis like

(D) who had established a mosque in the building, using the Acropolis to be

(E) establishing a mosque in the building and using the Acropolis as

Choice A, the best answer, correctly supplies the past tense verbs established and used to describe two actions performed in 1456; also, it idiomatically employs the phrase used the Acropolis as a fortress, in which used as means “employed in the capacity of.” Choices B and C incorrectly replace as with like. Furthermore, in C, when he had established a mosque distorts the intended meaning by stating that the first action was completed before the second was begun. Similarly, in D, had established... using states that Mohammed had already performed the actions before capturing Athens; and in E, establishing and using modify Athens, thus producing an absurd statement. In addition, D includes the unidiomatic construction “using x to be y.”

why "had established" is wrong? thanks for your any explanation!

If D is changed to "who had established a mosque in the building, using the

Acropolis as", is it more preferrable than A?

Why I feel the past perfect tense should be used here?