Simple answer- All of them.
Medium answer- The hue of the 2nd is more of a green, while the 3rd is more of a cyan-blue mix. The first one is blue.
Complicated answer- The way that light refracts on an object shows that the said object absorbs all colors except the one you see because that color reflects your eyes. So since 1 and 3 appear blue, neither are, and the answer is 2.
Impossible mode answer- Because of the way your brain takes information from your eyes and turns it into the world around you, colors do not truly exist. Colors are simply the work of your brain's processing and therefore no color can truly be blue because if you were to show another organism with a different brain than a human's, then they would not see blue. After all, their brain is not made to process the color, so they will see something else. So the answer is none of these are blue because blue is a non-consistent concept.
I've done way too much research on colors and the way your brain perceives them. I blame Brain Games and art tutorials.
My favorite hue is all colors. White is a reflection of all colors, and it doesn't change for anybody. Pink is the color for love and passion. Red is the color of blood and therefore life. Orange is a warm fall color. Yellow is bright and vibrant. Green is the color of nature. Cyan is often forgotten but still present. Blue is calm and beautiful. Purple is peaceful and related to royalty. Black is the absorption of all colors, and it takes in the positives and negatives of all other colors. I can't pick a specific color, considering I can't even pick a hue. If I did pick a hue, I'd still have to pick value and saturation, and I can't.
