A: Teachers encourage people to go to college, so an increase in the number of teachers leads to an increase in the number of college graduates.
B: Some college graduates choose teaching as a profession after graduating, so an increase in the number of college graduates also leads to an increase in the number of teachers.
C: There are more college graduates and teachers in higher income cities, so income is a confounding variable here, make it difficult to prove causation between number of teachers and number of college graduates.
D: Cities with a higher population have more teachers and more college graduates, so the correlation is due to a third variable (population of city).
E: The provided data is insufficient, so it is extremely difficult to establish the reason for the correlation.
F: Most college students choose non-teaching professions after graduating, which explains the correlation.
G: In Australia, college students are encouraged by their teachers to choose teaching as a profession after graduating.
