Final answer:
Option D ('The teeter-totter was shared by the boys.') is the sentence that is written in passive voice, as it fits the criteria of having the subject acted upon, including a form of the 'to be' verb, and it can include 'by' followed by the noun phrase.
Step-by-step explanation:
To determine which sentence is in passive voice, we look for key characteristics that differentiate it from active voice. In passive constructions, the subject is not the doer of the action but is being acted upon. There is often a form of the verb "to be" (am, is, are, was, were) coupled with the past participle of the verb (-ed, -en, for regular and irregular verbs respectively), and sometimes the preposition "by" followed by the agent performing the action. Considering the given options, choice D - "The teeter-totter was shared by the boys." is the sentence written in passive voice because "The teeter-totter" (the subject) is not performing an action but is experiencing the action of being shared, "was shared" is the verb phrase indicating passive voice, and it includes the prepositional phrase "by the boys."