You are given three grids, where each of them is 5 by 5 in size.
Grids have empty cells marked with "▢" and filled cells marked with "X".
Your task is to generate a referring expression that best describes the target grid while distinguishing it from the two other distractor grids.
The first grid is the target grid, and the following two grids are the distractors.

Target grid:

X X X X X
X X X X X
X X X X X
▢ ▢ ▢ ▢ ▢
X X X X X

Distractor grid 1:

▢ ▢ ▢ ▢ ▢
X X X X X
X X X X X
X X X X X
X X X X X

Distractor grid 2:

X X X X X
▢ ▢ ▢ ▢ ▢
X X X X X
X X X X X
X X X X X

Instruction: Describe the target grid.
Generate the referring expression starting with the tag "Expression: " for the given target grid. Omit any other text.
Expression: The grid with a row of empty cells at the bottom. 

assistant
Expression: The target grid has a unique pattern of "X" and "▢" where the bottom row consists entirely of empty cells, while the other rows have a mix of filled and empty cells. This distinguishes it from the distractors, where the bottom row is filled with "X" in distractor grid 1 and starts with empty cells in distractor grid 2.
assistant