Choose the correct options to complete the sentences

1. I'm looking at the stranger
   [which|when|who] was in front of my house in the morning.
2. We stayed at the same hotel
   [whose|when|where] ​we stayed last year.
3. I wonder
   [whose|who|where] mobile phone is left on the table.
4. The poem
   [what|which|whose] she wrote, was wonderful.
5. I don't understand
   [which|that|why] she is so angry with me.