Answer: Christina can hold Randy liable for the check
Step-by-step explanation:
In this scenario it is important to note 2 things.
1. Nina PAID Randy.
2. Randy PAID Christina.
The point is that Randy is the one who had a contract with Nina. Even though Nina is the one who's check was not honored, Christina has NO CONTRACT with Nina. This means she cannot hold her liable.
As far as Christina is concerned, the check came from Randy and so she should hold him liable.
Randy on his part can then go back to Nina and hold her liable because he is the one who had a contract with her.
If you need any clarification do comment.