The correct option is
D picturesque
In this sentence we would be looking for a word which best expresses "vivid" from the given options
Vivid means producing powerful feelings or strong, clear images in the mind.
If we look into the given options,
Brilliant means exceptionally clever or talented.
Fresh means recently made or obtained; not tinned, frozen, or otherwise preserved
explanatory means serving to explain something
picturesque means visually attractive, especially in a quaint or charming way
Option D is correct