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

Distractor grid 1:

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

Distractor grid 2:

▢ 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 target grid has a horizontal line of three filled cells at the top, a single filled cell in the second row from the top positioned fourth from the left, a T-shaped formation of filled cells in the middle with the base of the T in the third row and the stem extending up and down from the middle, a single filled cell in the fourth row second from the left, and two filled cells at the bottom right corner.
assistant
Expression: The grid with four "X" marks in the top row, two "X" marks in the second row, one "X" mark in the third row, and all cells in the fourth row being empty squares.
assistant