Answer:
because the government controlled all oil reserves
Explanation:
The massacre of Tlatelolco was the murder of students and civilians by the military and police on October 2, 1968, in the Plaza de las Tres Culturas in the Tlatelolco section of Mexico City. The events are considered part of the dirty war in Mexico, when the government used its forces to repress political opposition. The massacre occurred ten days before the opening of the 1968 Mexico Olympics.
The Mexican government invested $ 150 million in preparation for the 1968 Olympic Games to be held in Mexico City. The president of Mexico, Gustavo Díaz Ordaz, fought to keep the peace at a time of growing social tension, but his administration repressed the movements of independent unions, farmers, and took drastic measures when trying to direct the economy. In 1958, under the previous administration of Adolfo López Mateos, union leader Demetrio Vallejo had tried to organize independent rail unions, which the Mexican government quickly ended. Arrested Vallejo under a violation of Article 145 of the Criminal Code, which defined the "social dissolution" as a crime.
The student movement in Mexico City grew rapidly as a result of the reaction to the violent repression of the struggles between rival "gangs," which included large segments of students who were dissatisfied with the PRI regime. Sergio Zermeño has argued that students were united by a desire for democracy, but their understanding of what democracy meant varied widely.