The expression should be added to sentence 2 to best clarify the relationship among Paco's ideas is However
Explanation:
"(1) Today, even many blue-collar, retail, and clerical jobs require applicants to have a college degree. (2)"However" going to college—even a public college—is becoming more and more expensive." is the correct way to clarify the ideas, since "However" connects two contradictory ideas and at the same time it shows it shows the second sentence as an impediment to getting a good education which is a requirement to get a job, even for the ones that are not too demanding.
