Question

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

Answer 1

Sea floor spreading is you'r answer. <span />

Answer 2

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! =)