Mexican leaders after the revolution primarily sought to protect democratic rule by passing a new constitution in 1917 that included reforms for social justice, labor rights, and public education. This constitution was essential in establishing a modern state and securing citizens' rights. Although other measures were taken, the approval of the constitution was the most significant step in preserving democracy in Mexico. ;
Mexican leaders sought to protect democratic rule after the revolution primarily by passing a new constitution in 1917, which included reforms for social justice and labor rights. This constitution was essential in establishing modern governance and securing citizens' rights. Therefore, the correct answer is D: They approved a new constitution.
;