What is the length of line segment AB? All / s are equal,

Question

What is the length of line segment AB? All   /  s are equal, all   /  s too.
All lines that meet are perpendicular.

1)   /   = 4
2)   /   = 2

Source: Barron's

2 is definitely sufficient since you can add the 3 vertical lines on the left side (=6) and subtract the one on the right to calculate the length of   /  .
But how is 1 sufficient?

avikgt · Answer

The length of the vertical green line is equal to lengths of 2 vertical red lines. Therefore the length of the vertical green line is 2*2 = 4.

jamshedk · Answer

The 2 vertical red lines directly opposite the vertical green ie 2/(red line) = 4 ** 4/2 = 2
/ Red line = 2

vivesomnium · Answer

If you know the length of red line, through the diagram you can know the length of vertical green line as it is equal to two vertical red lines. this will be same as horizontal green line and hence length of AB can be found.
Similarly, if you know the length of green line, you can find length of red line and hence AB

Each alone is sufficient

nageshshiv · Answer

+1 for D
Red line is half of green line.

fluke · Answer

3R=1G+1R
2R=1G
Knowing either R or G gives the answer.

Ans: "D"

mustafagolam · Answer

Kudos to fluke. 
Visual inspection suggest, for length of AB, both 1) & 2) is required.

bumpbot · Answer

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What is the length of line segment AB? All / s are equal,

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