Answer:
B. Is the physical and emotional pain humans suffer worth it?
Step-by-step explanation:
Robert Frost highlights the "soul-and-body scars", which can be translated as physical and emotional hardships faced by humans. Frost then asks the "men of earth" if it is worth it to endure all of those hardships in order to be alive ("to pay for birth").
Therefore, the answer is alternative B. Is the physical and emotional pain humans suffer worth it?