We recommend that if you're testing 2 (or more) variations of a page all with similar text content that you no-index those variations.
Best practice would be to leave URL A as normal and set URL B, C & D as No-Index using your SEO plugin of choice.
An alternative option is to set the canonical URL on version B/C/D to version A in your SEO plugin of choice. If you're a beginner, I recommend sticking to no-indexing. Here is a good articles on canonical URL's from Yoast.