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
8%
0%
83%
8%
12
flagthe Netherlands
6%
6%
75%
12%
16
flagPakistan
0%
25%
75%
0%
12
flagGermany
6%
8%
73%
11%
80
flagAustria
0%
14%
71%
14%
14
flagthe United Arab Emirates
14%
0%
71%
7%
14
flagMalaysia
0%
7%
71%
21%
14
flagUnknown
7%
7%
70%
14%
27
flagAustralia
3%
11%
68%
16%
61
flagGreece
5%
0%
68%
26%
19
flagPoland
4%
8%
67%
18%
18492
flagthe United Kingdom
3%
10%
64%
19%
176
flagthe United States
5%
9%
59%
23%
683
flagIndia
8%
13%
51%
23%
246
flagthe Philippines
8%
8%
51%
27%
37
flagCanada
4%
12%
48%
34%
49
flagSouth Africa
7%
30%
46%
7%
13