What is the correlation between C. hiranonis and % secondary BAs?

• A. Positive correlation (ρ = 0.75)
• B. Negative correlation
• C. No correlation
• D. Inverse correlation with Pcorr < .05

Answer: (A)

The question tests how the abundance of a bile-acid–metabolizing bacterium relates to the fraction of secondary bile acids produced. A strong positive Spearman correlation (rho around 0.75) means that as C. hiranonis increases, the percent of secondary bile acids also increases. This fits the biology: C. hiranonis carries enzymes that convert primary bile acids into secondary ones, so higher bacterial abundance is expected to drive more conversion and raise secondary BAs.

The other patterns don’t fit the biology or the data. A negative correlation would imply the opposite relation, which isn’t plausible given the organism’s role. No correlation would suggest no link between the two measures, which contradicts the enzyme-driven conversion. An inverse correlation with Pcorr < .05 would still indicate a significant negative relationship, again at odds with the observed positive association.