Answer:
B. sie
In the conversation, William and Sven are discussing the need for groceries. Sven responds by saying "We will get them at the supermarket." The direct object in this sentence is "Lebensmittel" (groceries), which is plural. The direct object pronoun that corresponds to "Lebensmittel" in the sentence is "sie" (them). Therefore, the correct answer is B, "Wir bekommen sie im Supermarkt."