Problem : Can two-dimensional objects exist in three-dimensional space?

Yes. They simply exist in the same plane within space.

Problem : What is the minimum number of lines it takes to span space?

Three

Problem : Explain why three noncolinear points cannot form a three-dimensional object in space?

A plane can be created to contain any three points in space, therefore, three points isn't enough to create a three-dimensional object. It requires four noncoplanar points to form a three-dimensional object.