Final answer:
An fMRI study confirmed capacity of the fetus to hear at B. 38 to 39 weeks into the prenatal period by assessing brain response to auditory stimuli.
Step-by-step explanation:
The question addresses the development of fetal hearing and at what stage in prenatal development a fetus can respond to auditory stimuli as evidenced by brain activity on an fMRI study. According to the information provided, fetal hearing development occurs by the sixth month of development (24 weeks), which indicates that the fetus is capable of responding to sounds at this stage. However, the options in the question refer to later stages, suggesting that the question is asking specifically when fetuses have shown the capacity to hear through demonstrable brain responses.
Based on the developmental milestones provided, and knowing that the fetal stage extends to about 38 weeks after fertilization, it can be inferred that by 38 to 39 weeks (Option B), the fetus would not only have developed the physical structures required for hearing but would also likely demonstrate auditory response through brain activity. Therefore, the answer to the question is B. 38 to 39 weeks.