imo C

"Confused by the many strata and substrata of ancient civilizations overlying one another" , participle phrase should modify person i.e Schliemann

Rest of the choices are irrelevant.

(A) Schliemann’s excavations of the fabled city of Ilium, the ancient Troy, were temporarily called to a halt - Ruled out since Schliemann’s excavations cannot be Confused. Confused requires subject noun(person).
(B) Schliemann’s excavations of the fabled city of Ilium, the ancient Troy, temporarily halted-Ruled out since Schliemann’s excavations cannot be Confused. Confused requires subject noun(person).
(C) Schliemann temporarily halted his excavations of the fabled city of Ilium, the ancient Troy - active voice preferable than passive. So this is correct.
(D) excavations of the fabled city of Ilium, the ancient Troy, were temporarily halted by Schliemann- passive
(E) excavations of the fabled city of Ilium, and of the ancient Troy, were temporarily halted by Schliemann - passive also unnecessary and

same here, it has to be C.

This is a simple one.

There should be a direct relation between the word confused and the first word in the sentence after the comma. Only Schliemann can be confused. So it must be (C).