The correct answer is: collection of lunar rock samples.
The answer to the question is the collection of lunar rock samples. To determine the age of the moon, scientists have analyzed the composition and age of the rocks brought back from the moon during the Apollo missions. By studying these rocks, scientists can use radiometric dating techniques to determine their age. Radiometric dating involves measuring the decay of radioactive isotopes within the rocks to calculate their age. Therefore, the collection of lunar rock samples has been the most helpful in determining the age of the moon.