rRNA gene sequencing — The PCR/sequencing approach targeting rRNA genes from an unknown bacterium is most informative for determining:

Introduction / Context:
Ribosomal RNA (rRNA) genes, especially 16S rRNA in bacteria, are highly conserved with variable regions that allow phylogenetic placement. Sequencing these genes is a cornerstone of bacterial taxonomy and culture-independent community analysis.

Given Data / Assumptions:

• Amplified rRNA gene sequences are compared to databases for identification.
• rRNA genes contain conserved and variable regions suitable for phylogeny.
• Phenotypic traits like morphology or motility are not directly encoded in rRNA sequence patterns.

Concept / Approach:
By aligning the rRNA gene sequence against reference sequences, we infer evolutionary relationships and likely taxonomic identities (from phylum down to genus or species, depending on resolution). While certain lineages may correlate with metabolisms or morphologies, rRNA sequences do not directly specify those traits; they primarily inform relatedness.

Step-by-Step Solution:

Verification / Alternative check:
Consistent phylogenetic placement across multiple variable regions (e.g., V3–V4, V4–V5) strengthens identification, confirming relatedness.

Why Other Options Are Wrong:

• Morphology, metabolism, motility: phenotypic traits require microscopy or functional assays; rRNA sequencing alone does not define them.

Common Pitfalls:
Assuming 16S rRNA can always resolve to species; sometimes only genus-level identification is reliable, depending on divergence.

Final Answer:
the species to which the bacteria are most closely related