The correct answer is B) The speech that the computer science expert gave regarding online data mining was filled with information and was also very entertaining.
The sentence that should be revised to reduce wordiness is "The speech that the computer science expert gave regarding online data mining was filled with information and was also very entertaining."
In writing, the author must learn to go to the point. The idea must be clear, direct, and specific for a better understanding of the reader. After writing the text, you should check for grammar mistakes as well as spelling mistakes. But also you have to reduce wordiness, words or phrases that are redundant and has no need to be there in your sentence. If a word does not have any real meaning in the text, drop it.