Species A and B are in the same class.
<h3><u>Explanation:</u></h3>
The phylogenetic classification of the total living biosphere is differentiated into step like classifications where a bigger superheading contains different subheadings and so on. According to the most important classification headings, the categories are -
1. Kingdom
2. Phylum
3. Class
4. Order
5. Family
6. Genus
7. Species.
This classification can be easily remembered as the nemonic - Keep Pots Clean Or Family Gets Sick. Now this classification can be extended by adding a sub or supra to most of the categories.
So, within a kingdom, there are several phylum, and within a phylum, there are several classes and so on. So, two organisms belonging to same order must belong to same class. So, species A and B belong to same class.