Which lines are parallel?

blue and red only
green and red only
green, blue and red
none
This is a well known Zöllner illusion, first described in 1860. It may be caused by this impression of depth. The black lines are parallel, too!
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Very interesting!
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Answers by country

blue and red only
green and red only
green, blue and red
none
answers
flagAustria
0%
7%
85%
7%
28
flagSwitzerland
0%
5%
85%
10%
20
flagFrance
0%
6%
81%
12%
16
flagPakistan
0%
21%
78%
0%
14
flagSingapore
9%
6%
75%
9%
32
flagMalaysia
0%
6%
75%
18%
16
flagUnknown
7%
7%
70%
14%
27
flagGermany
3%
7%
69%
18%
198
flagAustralia
2%
11%
69%
15%
76
flagPoland
4%
8%
67%
18%
19476
flagthe United Arab Emirates
12%
8%
66%
8%
24
flagthe Netherlands
4%
4%
65%
21%
23
flagRepublic of Ireland
14%
7%
64%
14%
14
flagthe United Kingdom
2%
10%
63%
20%
219
flagGreece
4%
8%
62%
25%
24
flagthe United States
5%
8%
60%
24%
743
flagIndia
9%
11%
53%
23%
298
flagthe Philippines
7%
7%
50%
28%
38
flagSouth Africa
7%
28%
50%
7%
14
flagCanada
5%
11%
48%
33%
54