Do interaction diagrams for the use cases you elaborated $($fully dressed$)$ in Report #$1.$ You should do at least sequence diagrams, but you may do some other UML interaction diagrams, as well.

Describe what design principles you employ in the process of assigning responsibilities to objects. This can be done either as comment $$bubbles$$ in the diagram, or in the caption of the diagram.

Read the UML textbook about interaction diagrams and Section $2\mathrm{.}5\mathrm{.}1$ in the course lecture notes, in order to learn about good design principles $($for login$,$ browsing vehicle, create account, and reservation in car rental system$)$