Question

"The allure of artificial sweeteners lies in their sweetness without calories, yet debates persist regarding their metabolic impact. A 2023 study by Chen et al. explored how saccharin affected gut microbiota and glucose tolerance in mice. They observed that saccharin significantly altered microbial composition, leading to impaired glucose tolerance, suggesting a negative metabolic effect. However, a follow-up analysis by Garcia and Singh (2024) re-examined the original data, revealing that the mice receiving saccharin were also fed a higher-fat diet, a crucial confounding variable. When accounting for the diet, the microbial changes linked to saccharin showed no significant impact on glucose levels. Which choice best states the main purpose of the text?
a) To argue that the Chen et al. study was fundamentally flawed and should be disregarded.
b) To suggest that saccharin is metabolically benign when consumed in isolation.
c) To demonstrate how a confounding variable can obscure the true relationship between a sweetener and metabolism.
d) To highlight the importance of replication in scientific research, as shown by the Garcia and Singh analysis.

Answer 1

c) To demonstrate how a confounding variable can obscure the true relationship between a sweetener and metabolism.

Reason: the passage contrasts the original finding with a re-analysis that identifies a higher‑fat diet as a confounder, showing that accounting for it removes the saccharin–glucose effect.