According to the big bang theory, the universe—all of the stars, planets, and galaxies everywhere—began as a very small, dense mass. This mass expanded suddenly in an incredibly hot explosion-like event, and it has spent the last 13.7 billion years rapidly expanding and cooling.

In 1964, which of the following space technologies provided scientists with the best evidence that the universe was created in the big bang?
A.
a lunar module
B.
a Mars rover
C.
a radio telescope
D.
a weather satellite