What are the characteristics of the higher education system in Mexico?

The higher education system in Mexico is composed of public and private institutions.
Public institutions account for the majority of the student population.
The number of full-time professors has increased in recent years, with a significant proportion being under 40 years old.
During the expansion of the Mexican education system between 1970 and 1985, many individuals were hired without adequate qualifications, negatively impacting the quality of education.
a) I and III are correct.
b) II and IV are correct.
c) I, II, and III are correct.
d) I, II, III, and IV are correct.