The sentence should read as follows;
On July 20, 1969, Neil Armstrong landed the lunar spacecraft, The Eagle, on the moon.
So it wouldn't be the first one because July should be capitalized, proper because it's naming a particular month.
It wouldn't be the second because Neil Armstrong should be capitalized, proper because it's naming a particular man.
It wouldn't be the third because The Eagle should be capitalized, proper because it's naming the spacecraft.
So the answer is the fourth option
on the moon
Hope this helps. :)