Answer to the third puzzle: D

The simplest solution is to treat each line independently. Ignore everything else. Find the pattern in columns and rows. Is the line there? Is it not there?

Give it a try! :)

Solution rule and steps below


----------


>! Rule: In all rows and all columns, each line will appear exactly once
>! or twice. Never zero, and never three times.

>! How to Find Clues: In our solution column and row, we need lines that
>! appear twice, or lines that are missing twice. If a line appears
>! twice, it will not appear in our solution. If a line is missing twice,
>! it will appear in our solution. Ignore everything else.

>! Solve:

>! Step 1 - Narrow our answers

>! Look down column 3 for a common line or common missing line. 

>! There are two top line segments, so we cannot have an answer with a top line.
>! That eliminates A, B, E and F, leaving only C and D as possible
>! solutions.

>! Step 2 - Find our solution

>! Look across row 3 for a common line or common missing line.

>! The left vertical line is missing twice, so our answer must have a left
>! vertical line. C has no left vertical line. Therefore the answer is D.

>! Step 3 - Verify our solution
 
>! We can then "work backwards" and verify the solution both horizontally
>! and vertically for all other individual lines