You can implement a class that holds the fields you have in your JSON
class MyData
{
public string t;
public bool a;
public object[] data;
public string[][] type;
}
and then use the generic version of DeserializeObject:
MyData tmp = JsonConvert.DeserializeObject<MyData>(json);
foreach (string typeStr in tmp.type[0])
{
// Do something with typeStr
}
Documentation: Serializing and Deserializing JSON