Final answer:
China and the United States are the only countries that have sent spacecraft to the moon and successfully retrieved rocks from its surface.
Step-by-step explanation:
China is the only country, in addition to the United States, that has successfully sent a spacecraft to the moon and retrieved rocks from its surface. The United States achieved this feat through the Apollo program, which sent nine piloted spacecraft to the moon between 1968 and 1972, with 12 astronauts landing on its surface. China, on the other hand, has been active in lunar exploration in recent years, with three landers and a sample return mission. These missions have allowed scientists to study and analyze the lunar rocks, expanding our understanding of the moon's geology and history.