Final answer:
The medulla oblongata contains reflex centers that are crucial in regulating the respiratory rhythm in conjunction with lower brainstem centers. It includes the dorsal respiratory group (DRG) for the rhythmic regulation of breathing and the ventral respiratory group (VRG) for forced respiration. The pons, with its pontine respiratory group, also contributes to fine-tuning this regulation. The correct option is B.
Step-by-step explanation:
The brain structure that contains reflex centers involved in regulating respiratory rhythm, in conjunction with lower brainstem centers, is the medulla oblongata. The medulla oblongata includes the dorsal respiratory group (DRG) and the ventral respiratory group (VRG), which are crucial in maintaining breathing rhythm and forced breathing, respectively.
While the DRG controls the rhythm of breathing by stimulating muscles necessary for inspiration, the VRG is responsible for activation of accessory muscles during forced respiration.
Furthermore, the pons also plays a significant role in breathing regulation, which includes the pontine respiratory group composed of the apneustic and pneumotaxic centers. These pontine centers fine-tune the breathing rhythm set by the medulla by controlling the intensity and rate of respiration.
The other options, such as the hypothalamus and the cerebral cortex, influence the respiratory rhythm. The hypothalamus affects respiration in response to emotions, pain, and temperature, while the cerebral cortex can exert voluntary control over breathing during activities such as speaking or singing.