The correct option is D There was so much noise that I couldn't hear the speech.
A conjunction combines or connects two sentences as one. They can be a word or a phrase (like even if, as well as, etc). Correlative conjunctions are words in pairs that connect two sentences, but they're not written together, for example, either...or, but...and, such...that etc. 'So that' and 'so...that' have different meanings. 'So that' refers to purpose, it expresses the reason for which an action is carried out, as in 'I left early so that I could attend the party'. The given sentence does not focus on purpose, but the result, where 'so' emphasizes on "much noise" and it creates the effect "couldn't hear the speech", this can be seen in option D, hence it's correct. In option A, 'so that' has been used, it changes the meaning of the sentence, making it focus on purpose, the sentence means that noise was created for the purpose that the speaker can't hear, which is not logical, hence A is incorrect. Option B is grammatically incorrect, 'that the speech' is the error, hence option B is incorrect. Option C is also not grammatically correct, the sentence sounds poetic because of "so much noise there was", which isn't required here, hence option C is incorrect.