New mexico's internal challenges to becoming a state included a. the lack of railroads. b. difficulties with land and water rights. c. issues over slavery and international trade. d. all of the above.

The answer is B. difficulties with land and water rights.
This water rights become an issue because people in New Mexico have to move the water from indian and hispanic territories for their usage.
Since they live under spanish law during that time, they need to obtain the right to use land and water through Spanish empire's administrative grant