A citizen's duties refer to the responsibilities and obligations that are required of them by the state or society in which they live. These duties can include defending the nation, obeying the laws, paying taxes, serving on a jury, or participating in the democratic process. However, giving alms to the poor is not typically considered a duty of citizenship, but rather a charitable act that individuals may choose to do on their own. Therefore, the correct answer is giving alms to the poor.