The correct option is option D ("Prescient").
Prescient is an adjective that refers to the ability of perceiving and understanding events before they even unfold. This is certainly not a common word that you hear every day, it's something extra. So if we're talking about language using a cake as a metaphor, a rare word like "prescient" would liken to an extra ingredient that you add on top, such as frosting on a cake.
Hope this helps!