Based on prior knowledge, the feature "safety" is expected to have a positive correlation with the task of rating the decision to buy a car. A higher safety rating would generally correspond to a more positive rating of the decision to buy the car.

Based on this analysis, the possible values of the "safety" feature for each target class are as follows:

```json
{
	"unacceptable": ["low"],
	"acceptable": ["low", "med"],
	"good": ["med", "high"],
	"very good": ["high"]
}
```

Note that the values "low", "med", and "high" correspond to the categories of the "safety" feature. The dictionary above indicates that for the target class "unacceptable", the only possible value of "safety" is "low". For the target class "acceptable", both "low" and "med" are possible values of "safety". Similarly, for the target class "good", both "med" and "high" are possible values, and for the target class "very good", the only possible value is "high".