My sister sent me this pattern sequence. Please excuse the bad image quality.
I think it must be
Rule for plus signs: Every plus sign must be connected with another plus sign in the neighboring cell.
Rule for triangles: Last cell of each row contains the triangles that are present in all three prior cells.
The only option this works with is the mentioned one
The connection is between the crosses which are closest to the sides and to vertices.
On the first row 5 crosses are close to the sides and 1 cross to the vertex.
On the second row 5 crosses are close to the vertices and 1 close to the side.
On the third row 3 crosses are close to the sides and 3 crosses close to the vertices.
On the fourth row 1 cross is close to the side and 2 crosses close to the vertices.
If we add to the empty space the card on the bottom right, then we have 2 crosses close to the sides of the triangle. So my answer is the bottom, right card.