The sentence uses the words 'was delivering' which indicates that it is in the past continuous tense. The passive form of the sentence must maintain this tense. Option A) contains the words 'is being delivered' which is in the present continuous tense. Hence, it is incorrect. Option B) is incorrect because it has 'is delivered' which is in the past tense. Option C) indicates that the lecture is complete and not an ongoing process as is indicated by the original sentence.