Statements:
All Series is Chain
Only a few String is Chain
No String is Cycle

All Chain can never be Cycle: Only a few String is Chain means some String is Chain and No String is Chain. No String is Cycle. Thus, the Chain which is String can never be Cycle.. So, conclusion I follows.
Some String being Series is a possibility: There is no definite relation between String and Series. Thus, there is a possibility of some String being Series. So, conclusion II follows.
Hence, both conclusions I and II follows.