Best possible widget

Hi community,

I want to show the UI as shown below.

product01

              project01

                            requirement01

                            requirement02

               project02

                            requirement01

product02

              project01

                           requirement01

product03

and so on.

after clicking project 01 it would show all the requirements related to that project and if I click requirement01 it would show all the requirement details.

what are the best practices and widgets can be used.

regards,

madhu