A. but his notions at the time
were not accompanying substantial evidence.
B.
and his notions at the time had not accompanied substantial evidence.
C.
and even though his notions at the time was not accompanied by substantial evidence.
D. although his notions at the time were not accompanied by substantial evidence.
E. but
without accompanying his notions at the time with substantial evidence.
Option B and C: Meaning Error - Incorrect coordinating conjunction and is used in both the option, and hence the meaning is distorted; instead, contrasting coordinating conjunctions such as but or although must be used to emphasize the contrast in both the events. Hence B and C are out.
Option A and E: Tense Error - Incorrect usage of Tense. Past continuous incorrect in this case because in the time, i.e. in the past clearly shows a past action that is already complete. Hence, use simple past to show the completed action. In option E, the phrase "but without accompanying" is awkward.
Option D: Resolves the meaning and tense issues. Hence, the correct option is answer choice D.