The correct answer is C. The problem that was solved during Sojourner Truth's lifetime was slavery, as it was abolished after the Civil War. The Emancipation Proclamation was issued on January 1, 1863, during the war, in the States of the Union. Then, to ensure the abolition of slavery throughout the United States, Lincoln pushed for the approval of the Thirteenth Amendment, and insisted that reconstruction plans for the southern states required abolition in the new state constitutions. The Congress passed the 13th Amendment on January 31, 1865, and was ratified by the states on December 6, 1865, ending slavery in the United States of America.