Agriculture has no impact on the levels of organic content in soil because organic matter is plowed back into the soil every year.
a. true
b. false

False, Agriculture greatly alters the composition of the organic content of the soil. The soil nutrients completely depend on the crop that has been grown in this location the prior several growing seasons. Many crops use high levels of nitrogen and phosphorus and therefore leave the soil lacking these nutrients. Reworking the left over material into the soil after the crops helps a little but crop cycling is required to really replenish the soil. This would mean planting crops the add nutrients back into the soil such as legumes.

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. 

D. a mountain abd are made by volcanos and tectonic plates