The correct answer is B. Because
Step-by-step explanation:
In language, a conjunction is a word used to connect different clauses or sentences and that shows the relationship between the elements connected. In the case of Hava, as she wants to explain a reason or explanation she should select conjunction related to cause such as because, as, for the reason that, etc. Therefore, the word that completes the sentence "I visited Poland _____ my parents were born there" is because as this is the only conjunction that expresses the relationship of cause or explanation in the sentence.