Final answer:
In the letter, Carlos is encouraging Carina to visit his town and attend the local university. The correct form to complete the letter is conocer. Personal a is not necessary in this context.
Step-by-step explanation:
In the letter, Carlos is encouraging Carina to visit the town where he lives and possibly attend the local university. Therefore, the correct form to complete the letter is conocer. Carlos wants Carina to become familiar with the town and its university, which requires knowing or being acquainted with the place. In this context, a personal a is not necessary, so you can place an x in the blank.