Re: Although some had accused Smith, the firms network manager, of neglig

There are two problems in option E:

... a quite tense situation by publicly stating the debacle not to have been Smiths fault.

1. A quite tense situation is not the right way to express that idea. For example:

She solved a question that was quite tough. This one is fine.
vs.
She solved a quite tough question. This is not correct.

He watched a movie that was quite long. This one is fine.
vs.
He watched a quite long movie. This is not correct.

2. Stating that the debacle was not Smiths fault is better (more direct) than stating the debacle not to have been Smiths fault.