Not sure about this one.
The obvious answer for the red and blue rows is:
Rotate the first figure 180 degrees. XOR with the second figure. (Draw a line where exactly one figure has a line.)
However that leads to the following result for the black row:
Which is not one of the available options.
I can't see any other consistent explanation that works for both the red and blue row.
There are other ways of expressing this answer (E.g. You could mirror the first figure horizontally, mirror the second figure vertically, XOR them, then mirror the result vertically), but you end up with the same result as above for the black row.
You can probably find some rules to explain all patterns from A to H. But as I understand these type of puzzles, the "simplest" and "most obvious" rule might/should be the intended one. The question is how many steps and "if"s are acceptable?
Here is an explanation for pattern...
Honestly, I don't think that this is the intended solution...
vertically flip patterns in column2 if not (vertically) symmetric else flip pattern in column1
overlay with pattern in other column
remove double overlaying horizontal lines