Final answer:
Martin Luther King, Jr. feels certain of ultimate victory in the struggle for civil rights near the end of 'Letter from Birmingham Jail' because of the strong financial support of the civil rights movement.
Step-by-step explanation:
Martin Luther King, Jr. feels certain of ultimate victory in the struggle for civil rights near the end of 'Letter from Birmingham Jail' because he knows that the civil rights movement is better funded than those who oppose them.