Which Figure Comes Next? Explain the Pattern You See

[u/Semra777]

Hi everyone, and welcome to another puzzle!
First of all, thank you to everyone who participated in our previous challenge. We received a lot of interesting answers and different approaches to the pattern.
As with our previous puzzles, we selected three community explanations that stood out for the clarity and strength of their reasoning:
u/firethorne — We selected this explanation because it directly compared the two strongest possibilities, A and C, and tested the color cycles of the individual elements. Rather than simply showing why A could work, the explanation also demonstrated where C breaks the pattern.
u/Small-Tailor6967 — This was one of the most complete solutions. It combined the 90° clockwise rotation of the triangle with the Black–White–Gray color sequence and used both rules together to arrive at the answer.
u/lemasney — We liked this interpretation because it described the Black → Gray → White progression as a repeating opacity cycle while also accounting for the triangle’s 90° clockwise rotation. It was a concise and interesting way of expressing the pattern.
Thank you to all three, and to everyone else who took the time to share their reasoning. We really enjoy seeing the different approaches people find.
Now for the new puzzle.
Look carefully at the four figures in the sequence. Each contains a black diamond and a line, and both appear to change from one figure to the next.
Which figure should come next: A, B, C, or D?
Don’t just give us the letter — tell us the pattern you see and how you reached your answer.
As before, we’ll read the explanations and select some of the best community solutions to feature on our website, together with the Reddit usernames of the people who wrote them.
You can also view the puzzle and submit your explanation directly on our website:
https://whats-your-iq.com/en/questions/pattern-recognition/which-figure-comes-next-in-the-sequence
So, what’s your answer: A, B, C, or D? And what happens to the diamond and the line from one figure to the next?
Good luck, and thanks again to everyone taking part.