GMAT Sentence Correction (SC) | Re: At a recent conference, the Transit Authority has stated

Verb tense rules: Unless there is a REASON, keep the tenses in the verb SIMPLE (simple>progressive or perfect) and CONSISTENT (Change tenses only if you have to)
will failed: future + past - incorrect usage! E eliminated.
Recent conferece means the conference is already over: simple past should suffice here. there is no reason for the use of past perfect - only when a later past action is present in the sentence. this is not the case here. the only other action - failing - happens before the