Which of the following statements are true according to our material? Group of answer choices (A) Amazon Mechanical Turk, YouTube, Twitter, Wikipedia represent different crowdsourcing platform. (B) Youtube is an incentive based crowdsourcing platform. (C) Amazon Mechanical Turk and Wikipedia are two voluntary crowdsourcing platforms. (D) A crowd sourcing platform will ask crowd to carry out human intelligent tasks and perform crowd answer analytics to identify and integrate crowd intelligence with machine intelligence. (E) How to put human in the loop for crowd answer analytics is one of the key differentiation factors for crowd computing services