Directions: Choose appropriate meaning of the words in bold as per their contextual use.

It's an invaluable textbook because its pellucid prose makes difficult concepts easy to grasp.

Pellucid means exceptionally clear or transparent, describing writing that is crystal clear and easy to understand. While transparent (A) is a literal meaning, in the context of explanatory prose, explicit (D) better captures the sense of writing that makes difficult concepts completely clear and unmistakable. Pure (B) and serene (C) are unrelated to clarity of expression.