One of my close friends made great progress in her studies so her teachers ____ her, and I _____ her. [ ]

A. were happy with; was happy with

B. were happy for; was happy for

C. were happy with; was happy for

D. were happy for; was happy with

甲出国探亲，将自有的精美玉石托付好友乙保管，乙也是玉石收藏家和玉石雕刻家。一日，某展览会通知乙举办玉石展览，乙将自己收藏的玉石和甲托其保管的玉石都拿到展览会参展。展会期间，数人称赞甲的玉石精美，若刻成玉雕，价值连城。展览会结束后，乙将甲的玉石刻成玉雕，使玉石价值倍增。外国友人丙来乙家做客，执意出高价购买该玉雕，乙将该玉雕出售。

本案发生的债权关系有（）

A、保管合同关系和不适当的无因管理关系

B、不当得利关系和侵权行为关系