I am getting an error, Inconsistent accessibility: return type " " is less accessible than " ".

Not sure what is going on, I would appreciate some help

```
public List<point2d> get_myList(ReturnData3 rd)
{
List<point2d> points = new List<point2d>();
List<double> x = rd.X3;
List<double> y = rd.Y3;
int h = rd.CounT;
for (int i = 0; i < h; i++)
{
points.Add(new point2d(x[i], y[i]));
}
return points;
}
//
//
//bubble sort
//
//
public List<point2d> sortPoint(ReturnData3 rd, XY p,List<point2d> k) //sorts array, bubble sort method, least to greatest
{
List<point2d> sort = new List<point2d>();
bool flag = true;
int size = rd.CounT - 1;
while (flag)
{
int h = 1;
flag = false; //set flag to false, start loop
for (int i = 0; i < size; i++)
{
if ( k[h].x < k[i].x) //gets second x and compares it to the first x
{
double temp_x = k[i].x;
double temp_y = k[i].y; //keeping (x,y) together
k[i].x = k[h].x; //changes x (main sort)
k[i].y = k[h].y; //changes y
k[h].x = temp_x;
k[h].y = temp_y;
flag = true; //made the swap
sort.Add(new point2d(temp_x,temp_y)); //stores into new list (sort(x,y))
}
sort.Add(new point2d(k[i].x, k[i].y)); //stores if already in the right spot
size--;
}
}
return sort; //trying to return sorted mylist
}
```