Rearrange the jumbled parts (P, Q, R, S) to complete the sentence logically: Research into the 'gut-brain axis' has revealed that the microbial community inhabiting the human digestive tract plays a vital role in regulating mood and cognition _______________________________________________ potentially revolutionizing the way we treat chronic depression and anxiety. P. as the composition of this microbiome is influenced by diet, stress, and environmental exposures Q. by producing neurotransmitters like serotonin and dopamine that communicate directly with the central nervous system R. effectively making the gut a 'second brain' that can either promote mental resilience or trigger systemic inflammation S. through the vagus nerve and various biochemical signaling pathways that bridge the enteric and cranial regions