Need help!! Land and Water Forms on the Earth's Surface (Continued)

What is an important "idea" fact that you learned in this lesson??

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. 

Ithink the answer is d.

Conditions are more like living on  land  for creatures in the upper part of the intertidal, which is only covered with  water  at extreme high tide, so life is easier on land. conditions are more like living in the ocean for creatures in the lower part of the intertidal which is only exposed to air at extreme low tide. so basically it both worlds of land and ocean.

i need the choices if i am going to answer this question.