The correct answer is: A. He was chased by a big crowd and later was arrested by the police.
The other options are incorrect because they do not correctly reflect the order of events. In option B, the police arrested him before he was chased by the crowd. In option C, the police arrested him before he was chased by the crowd and was later. In option D, the police arrested him before he was chased by the crowd and was later arrested by the police.
The sentence “A big crowd chased him and later the police arrested him” can be paraphrased as “He was chased by a big crowd and later was arrested by the police.” This means that the crowd chased him first and then the police arrested him.