I will never forget the day ___ we worked together in London

I will never forget the day ___ we worked together in London.
A.when B.on that C.which D.while
I will never forget the day ___ we spend together.
A.when B.on that C.which D.while
Was it in cinema ___Bob met you ___you saw the film?
A.that,that B.whom,that C.where,that D.which,where