What is primarily responsible for expressive language and is located in the frontal lobe?

Broca's area is primarily responsible for expressive language and is located in the frontal lobe. This region is critical in the production of speech and language processing. It plays a key role in the ability to formulate words and construct grammatically correct sentences, reflecting its function in expressive language. Damage to Broca's area can lead to Broca's aphasia, characterized by difficulty in speech production while comprehension remains relatively intact.

The prefrontal cortex, while involved in higher cognitive functions and decision-making, is not specifically responsible for language expression. Wernicke's area, located in the temporal lobe, is associated with language comprehension rather than production. The primary motor cortex is responsible for motor control, including the muscles involved in speech, but it does not specifically handle language expression itself. Therefore, Broca's area is distinctly recognized for its role in expressive language, making it the correct answer.