Ersatz means (of a product) made or used as a substitute, typically an inferior one, for something else.
Ex: ersatz coffee"
Chaotic means in a state of complete confusion and disorder.
Ex: the political situation was chaotic
Artificial means (of a person or their behaviour) insincere or affected.
Ex: she gave an artificial smile
Impromptu means done without being planned or rehearsed.
Ex: an impromptu press conference
vague means of uncertain, indefinite, or unclear character or meaning.
Ex: many patients suffer vague symptoms
Thus option (B) is the correct choice.