Here's why:

* Lunar Orbiter 1 was launched in 1966 and was the first spacecraft to orbit the Moon and take detailed photographs of its surface. These photographs were crucial for selecting landing sites for the Apollo missions.

Let's look at the other options:

* Surveyor 1 was the first spacecraft to make a soft landing on the Moon in 1966. Its primary mission was to test landing technology and take pictures of the lunar surface, but it did not map the entire Moon.

* Ranger 7 was a probe that crashed into the Moon in 1964. While it took the first close-up images of the lunar surface, it didn't orbit the Moon and therefore didn't map it extensively.

* Luna 3 was a Soviet probe that flew around the Moon in 1959. It was the first spacecraft to take pictures of the Moon's far side, but the images were low resolution and didn't map the entire surface.

Therefore, Lunar Orbiter 1 is the correct answer as it was the first probe designed to extensively map the Moon's surface with high-resolution photographs.