To determine the correct pattern for the empty square, we need to analyze the sequence and pattern transformation in the given images.

Observe the transformation from the first square to the second square in the top row.

• The pattern inside the square is rotated 90 degrees clockwise.
• The triangle position remains the same but the internal shapes (rectangles and semicircle) rotate within the triangle.

Apply the same logic to the bottom row. The pattern in the given square should undergo the same transformation.

• Rotate the pattern 90 degrees clockwise.
• The current position of the L-shaped pattern will change orientation similar to the transformation modeled in the top row.

Compare the options and identify the one that matches the expected transformation.

• Option 3 matches the anticipated pattern after a 90-degree clockwise rotation of the L-shaped pattern.
• The other options do not fit the defined rotation pattern, thus can be ruled out.

Therefore, the correct pattern in the empty square is represented by Option 3.