To determine which rule would result in the eighth shape being a star, let's analyze each option to find the pattern:
-
star, square, triangle - This pattern repeats every 3 shapes. The sequence goes:
- 1st: star
- 2nd: square
- 3rd: triangle
- 4th: star
- 5th: square
- 6th: triangle
- 7th: star
- 8th: square (not a star)
-
star, square, triangle - Same as above.
- 1st: star
- 2nd: square
- 3rd: triangle
- 4th: star
- 5th: square
- 6th: triangle
- 7th: star
- 8th: square (not a star)
-
circle, triangle, star - This pattern also repeats every 3 shapes:
- 1st: circle
- 2nd: triangle
- 3rd: star
- 4th: circle
- 5th: triangle
- 6th: star
- 7th: circle
- 8th: triangle (not a star)
-
circle, triangle, star - Same as above.
- 1st: circle
- 2nd: triangle
- 3rd: star
- 4th: circle
- 5th: triangle
- 6th: star
- 7th: circle
- 8th: triangle (not a star)
-
circle, star - This pattern repeats every 2 shapes:
- 1st: circle
- 2nd: star
- 3rd: circle
- 4th: star
- 5th: circle
- 6th: star
- 7th: circle
- 8th: star (this is a star!)
-
star, square - This pattern also repeats every 2 shapes:
- 1st: star
- 2nd: square
- 3rd: star
- 4th: square
- 5th: star
- 6th: square
- 7th: star
- 8th: square (not a star)
From the analysis, the fifth option (circle, star) is the pattern where the eighth shape is a star.
So, the answer is: circle, star.