What is one hallmark of Wernicke aphasia?

Wernicke aphasia is characterized primarily by a significant difficulty in understanding spoken language, which makes option B the hallmark feature of this condition. Individuals with Wernicke aphasia may produce fluent speech that contains many words but lacks meaningful content, often resulting in nonsensical sentences. This occurs because the areas of the brain responsible for language comprehension are affected, leading to poor understanding of what others say and also affecting the coherence of their responses.

Although the other options can be associated with different types of aphasia or language processing disorders, they are not defining characteristics of Wernicke aphasia specifically. For instance, individuals with Wernicke aphasia may speak fluently without difficulty expressing their thoughts, thus making option A less applicable. Furthermore, while reading comprehension and writing may also be impacted, they are not as directly correlated to the core issue of understanding spoken language, which is the prominent sign of Wernicke aphasia. Therefore, the inability to comprehend spoken language stands out as the crucial diagnostic marker in this condition.