The correct answer is B. Visits
Step-by-step explanation:
In English grammar, when an action is usual, the most appropriate tense is the Simple Present; this applies to hobbies, usual events, routines, among others. This implies in the case of "My family __ Sebago Lake in Casco, Maine, every year" the best is to use the simple present as the section "every year" shows this is a usual action of the event. Additionally, in the simple present, the verb is the same as the infinitive form without the preposition "to" for example, "I run every day". Additionally, in the case of third-personal singular pronouns or nouns "-s" or "-es", for example, "She runs every day".
According to this, the correct verb in the sentence presented is "visits" because this follows the Simple Present structure that is appropriate for usual events including the "s" at the end of the verb considering "My family" is a third-person singular noun.