The following list best summarizes conditions that are unique to earth because they are "just right" to support life:
a. temperature or amount of radiation from the sun, gravity, atmosphere, and water
b. water, a moon, and a lithosphere
c. atmosphere, gravity, water, and a cryosphere
d. differentiated composition, water, atmosphere, and a lithosphere

For this item, the most probable answer is letter A. One of the most important reason why Earth is a livable place is its proper distance from the Sun which gives adequate temperature and amount of radiation. Other factors are the gravity, atmosphere, and water. 

Humans have survived and thrived in mexico city by using technology to create greater access to land. when the spanish conquered the aztec capital, tenochtitlan, in the 16th century, they built mexico city by draining the lakes and filling in the lake water to create more arable land for agriculture. this technique of land reclamation has continued to be fundamental to human civilization in mexico city.