"REGARD AS" and "CONSIDER TO BE"

Many historians regard the time of the Heian court as the greatest period in Japanese history.
A. Same
B. regard the time of the Heian court to be
C. regard the time of the Heian court to have been
D. consider that the time of the Heian court is
E. consider the time of the Heian court as

The correct relevant idiomatic expression are "regard as" and "consider to be". Eliminate B, C and E. D is wrong tense. A is correct.

sentence with-
consider as   X
regard to be  X