Step 1: Find the label attached to each shape. Each shape carries a fixed label: + marks a square, C marks a triangle, T marks a circle, and this pairing never changes anywhere in the grid.
Step 2: Track how the shapes shift across each row. Row 1 order is square, triangle, circle. Row 2 order is triangle, circle, square. Row 3 order so far is circle, square, and then the missing shape. Each row shifts the row above one position to the left with wraparound, so row 3 must end with a triangle, which carries the C label.
Step 3: Track the shading pattern. Every row has exactly two shaded shapes and one unshaded shape. Row 3 already shows the circle shaded and the square unshaded, so the missing triangle must be shaded to keep two shaded shapes in that row.
Step 4: Match this to the bottom-row images. The missing piece must be a shaded triangle labelled C. Image 6 is a shaded triangle with the C label, image 4 is a shaded triangle but with a T label, and image 1 is a shaded square, not a triangle. Only image 6 fits both the shape-label rule and the shading rule.
Final Answer: Image 6 replaces the question mark, so the answer is option B. \[ \boxed{\text{Image 6}} \]
