Which is the most challenging problem facing many tribal governments?

lack of revenue because of poverty

high rents because of housing booms

not enough workers to fill available jobs

reservations located far from cities

lack of revenue because of poverty

Explanation:

Native American Reservations are among the poorest regions in the United States. The poverty rate in some of these reservations is over 50%, way higher than the national average of around 12%.

Because of poverty, the tribal governments cannot obtain enough revenue in the form of taxes and contributions, and as a result, these governments are not effective in carrying out their tasks.