I believe the answer is #1. Adaptability depends on environment.. organisms adapt to environmental changes, and how their young with this trait can deal with those issues...
Locations along rivers meant faster travel upstream and downstream to rule territories. The city became the place where the ruler or rulers lived together in a stationary spot. The city's location along early rivers encouraged stronger government, which in turn encouraged stronger cities.
The asteroid belt lies between 2.2 and 3.2 astronomical units (AU) from our sun. One AU is the distance between the Earth and sun. So the width of the asteroid belt is roughly 1 AU, or 92 million miles (150 million km).