I am trying to improve my logical reasoning skills. Came across below question. See image. Can anybody let me know what the logical reasoning to the answer will be. I have no idea how to solve this

The question is, "Which of diagrams A, B, C, D, or E is the best continuation of the sequence in the top row?"
I tried to represnt the positions of x and o in a table, then in a graph to see if there is a visual pattern. The x (Blue) could be assumed to follows a pattern, 1,2,2,3,4 the next could be a 4. However, the pattern for O is not obvious. If you look at the difference $+ - o$, for each position you get the second graph, 5 looks logical at the 6th difference.
Accordingly, the value $(+,o)=(4,6)$ makes sense as the 6th position. So I would pick D as an answer.
In left most graph: Series 1 is data for + and Series 2 is data for O In the right graph: Series 1 is the difference between + and O