Applying UK visitors Visa from Germany

Dear All,

My parent is holding Indian passports. My parent has come to my sister's house in Germany and staying in Germany for next 3 months in Visitors visa.

Please help me with the below query.

1. Can my parent apply for UK Visitors visa from Germany?
2. If they are allowed to apply UK visitors visa, then what address they should fill in the application it should be India or Germany address?

Thanks

1. Yes.
2. Probably German address.

Thanks.