Two tectonic plates under water move apart, and magma fills the space between them this is an example of

Stretching melted cheese apart from each other. 
because in this example, i have given, is it moving apart, and melted cheese, if you want to take it apart, it will not move closer.
Hope that this helps you! =)
Have a great day! =)

Ibelieve it's the pacific islands 

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.