Echo flower near the bench where the abandoned quiche can be found

[Moonborne]

Ok so many people think that Sans was the one who said "I just wasn't ready for the responsibility" BUT if you call Papyrus/Undyne 2 times Undyne will tell you that she and Alphys built the puzzle, and as the Undertale Wiki writes, Undyne was the one that told Alphys near the echo flower that she wasn't ready for the responsibility as she was just appointed as the Captain of the Royal Guard at that time. If I'm wrong, please correct me.