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
flagSingapore
10%
0%
80%
10%
10
flagthe Netherlands
7%
0%
76%
15%
13
flagGermany
7%
9%
72%
11%
54
flagGreece
9%
0%
72%
18%
11
flagMalaysia
0%
7%
71%
21%
14
flagthe United Arab Emirates
14%
0%
71%
7%
14
flagUnknown
7%
7%
70%
14%
27
flagAustralia
4%
6%
68%
20%
45
flagPoland
4%
8%
67%
18%
17651
flagthe United Kingdom
3%
10%
65%
18%
153
flagthe United States
5%
8%
60%
23%
649
flagthe Philippines
8%
8%
50%
27%
36
flagSouth Africa
0%
33%
50%
8%
12
flagIndia
8%
13%
49%
25%
218
flagCanada
4%
12%
46%
36%
47