Answer:
Species X and species Z belong to the domain
Explanation:
Coccus-shaped bacteria can be found in pairs, chains, squares of four, cubes of eight, or grape like clusters. More specificially, this type of bacteria found in pairs is called diplococcia, in chains is called streptococci, in squares of four is called tetrads, in cubes of eight is called sarcinae, and in grape like clusters called staphylocci.
I don’t know why they make everyone type more than 20 characters but B sounds like the most reasonable answer.