I believe the correct answer is: e. effortless production of meaningless speech.
A primary characteristic of Wernicke's aphasia is effortless production of meaningless speech, while speech retains a natural-sounding rhythm and a relatively normal syntax. This condition is caused due to the injury on Wernicke's area, a link between the left posterior section of the superior temporal gyrus and the reflexive mimicking of words and their syllables that associated the sensory and motor images of spoken words.