To answer this you need to take into consideration that the Americans chose non violence, and they preferred non-violent means of protests such as boycotts. Here the last answer is a violent form of resistance so it can not be correct. The first one does not make any historical sense, so we can't consider it and the third and the second could be correct. to determine which is correct we need to consider all the historical events and we can see that none of them indicate rule breaking or in this case not following the law, so the only logical answer has to be the THIRD one which is " by sending him petitions ", because they initially just wanted peaceful negotiations
Research ethics are general rules that are followed when doing experiments to insure that no permanent harm comes to the test subjects or anybody else as a result of the research. This is perhaps even more important in sociology because the test subjects are human.
