Final answer:
The sentence best paraphrased according to MLA guidelines is option B.
Step-by-step explanation:
The best paraphrase of the sentence "Despite the Trabi's lack of efficiency, it was very popular due to the limited availability of cars." according to MLA guidelines is option B. "Due to the limited availability of cars, the Trabi was very popular despite its lack of efficiency (Mann 114)." This paraphrase accurately captures the main ideas of the original sentence, highlighting the popularity of the Trabi despite its inefficiency because of the scarcity of cars.