What was the "porfiriato"?
a. a period in mexican history marked by the dictatorship of porfirio diaz and his wide spread corruption
b. a period in mexican history marked by the presidency of porfirio diaz and his policies of social justice
c. a period in mexican history marked by the election of porfirio diaz and his corrupt successors
d. a period in mexican history marked by the assassination of porfirio diaz and his generous sons?