Correct Answer:
B. was completed
This sentence is in the passive voice, indicated by "by the team". The action of completing the work was performed by the team. The keyword "yesterday" indicates that the action happened in the past. Therefore, the past simple passive voice is required. The structure for past simple passive is "was/were + past participle". Since "the work" is singular, "was completed" is the correct form. "Completed" (active voice) is incorrect. "Is completed" (present passive) and "has completed" (present perfect active) are incorrect because the action happened "yesterday".