A responsible citizen could best participate in serving their community by watching campaign ads on TV before going to vote.
registering for the selective service when they turn 18.
paying their federal income taxes on time each year.
driving a neighbor to their polling place on election day.

driving a neighbor to their polling place on election day.

Explanation:

Helping the community is always best displayed by the direct, concrete actions that help other members and people. This could be done by various volunteering works, donations, cleaning and resaturation, and helping anyone in need with the sources that we have. As voting is one of the key activities that responsible citizens should participate in, one must go to vote and help others to do so as well. Driving the neighbor to vote is a great example of being responsible, helping others be responsible, and serving other members of the community.