Final answer:
Movements often reserve civil disobedience for last because it carries legal risks, such as the potential for arrest. It's considered after peaceful and gradual methods like legislation and court cases have been tried and are deemed insufficient to effect the necessary change.
Step-by-step explanation:
The reason most movements use acts of civil disobedience as a last resort is primarily because they often involve violating laws, which includes the risk of arrest (D). Civil disobedience is a powerful tool for change that has been a part of significant movements throughout history, such as the African American civil rights movement. These tactics are effective in drawing attention to causes and effecting change, but they carry legal risks for participants. Movements use peaceful, gradual methods like passing laws and winning cases in court first, and then turn to civil disobedience when these methods have been exhausted or when they need to create a sense of urgency or a dramatic impact to bring widespread attention to their cause.
While some may argue it always leads to riots (A) or that it causes protestors to be seen as criminals (B), these are not inevitable outcomes. The use of social media (C) is often employed alongside civil disobedience to amplify the movement's message, but this alone isn't a primary reason acts of disobedience are used as a last resort. It's mainly the legal implications and potential for arrest that make it a method of last recourse after other non-confrontational measures have been tried.