when ever you are reporting a fact that happend in past you have to use simple past tense. In this question, a mere fact has been reported, so it will be a simple past form.
But the bigger issue here is
all the proceedings ..........were not
not all the preceedings ........were.
first one imples that the proceedings were not totally carried out.
where as the second one imples that part of the proceedings were not carried it.
looking at the ununderlined portion.....Soviet audiences have seen a great deal of coverage. we need to choose the second option.
so E is the correct answer.