Given below are a few sentences with one blank in each. Below each sentence are given four words among which one word might fill the blank. If none of the words fill the blank to form a meaningful sentence, choose option 5 ‘None of the above’ as your answer. The professor's lectures are known for their ability to distil complex philosophical concepts into ___________ explanations that even those new to the subject can comprehend.

The sentence mentions that the professor's lectures can distil complex philosophical concepts into explanations that are easy to understand. "Lucid" means clear and easily understandable, making it an appropriate choice for describing the professor's explanations. The other options are incorrect: b) Luminous: This word means emitting light or bright, which doesn't apply to the concept of distilling complex concepts. c) Lethargic: This word means sluggish or lacking energy, which is opposite to the idea of clear explanations. a) Ludicrous: This word means ridiculous or absurd, which doesn't describe the quality of the professor's explanations.