Blender undesiredly merges objects into single object at export

Question

I have the following Blender structure:

When I export it as an obj with default export settings, I see the following if I import it for example into Unity:

As one can see, Blender merges the 4 objects into a single one. However, I don't want that.

I have tried changing the export settings, but none of my approaches kept the objects separate.

Can somebody explain why Blender merges my objects and how I could keep them separate (as children of a main object)?

This is what I tried and what didn't work:

Answer 1

I got it.

I unticked "Objects as OBJ Objects", and I unticked "Objects as OBJ Groups". Also, I ticked "Write Materials" and "Write Material Groups".

Here is a screenshot of the entire settings: