What threats do the bats of Barcken Cave face?

The correct answer is a)  a resource with a limited supply; it will run out.

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. 

Do you have a picture for this problem?

The correct answer is:   [b]:   "has no atmosphere" .