Consider the following statements :
- The primary key of a relation cannot contain null values.
- Unique Key can have null values.
Which among the following is true ?
- Both $\text{I}$ and $\text{II}$ are true
- Both $\text{I}$ and $\text{II}$ are false
- Only $\text{I}$ is true
- Only $\text{II}$ is true