PSAT Writing and Language Practice Question 689

Question: 689

Matter-Antimatter Asymmetry
It can be described as one of the greatest mysteries of modern physics. In a universe that 1 tends universally, as it were toward net neutrality, the apparently asymmetrical distribution of the baryon charge is a 2 singular and tantalizing puzzle. Atoms—and thus, matter, which composes the visible universe—possess a positive baryon charge equivalent to the number of protons and neutrons contained within the nucleus. Following physicist Carl D. Anderson's 1932 gamma ray 3 experiment which demonstrated the existence of antimatter, scientists anticipated the discovery of negatively charged baryon antimatter throughout the universe in quantities that would precisely counterbalance the positive baryon charge of matter. That discovery, thus far, has not been 4 unfound.
At odds with the Standard Model of physics, collision and radiation studies of antimatter 5 has consistently confounded scientists' efforts to reconcile the baryon asymmetry. In fact, the known universe appears to be dominated by up to 0.01 times more matter than antimatter. 6 Since this is such an influential quantity, such a discrepancy could soon prove to be a silver bullet for both the standard model and general relativity, whose tenets are entrenched in our understanding of everything from the interaction of subatomic particles 7 to the big bang theory of cosmology.
Physicists at UBC and TRIUMF have proposed scenarios in which the baryon asymmetry is resolved through the antimatter potentially extant in the dark matter regions of space. Dark matter— 8 unobserved material inferred to exist by its quantifiable gravitational effect on visible galaxies—is estimated to comprise roughly 23% of the universe by density. Visible atoms, 9 meanwhile, constitute less than 5%. The UBC and TRIUMF theories are hampered, however, by the inherent difficulties of studying the composition of dark matter. Currently, the most promising methods involve searching the sky for the spontaneous decay of protons, which—rarely, it must be acknowledged—may signify an atom's collision with a negative baryon dark matter particle.
Meanwhile, a research team at Fermilab known as the DZero Collaboration recently announced observations of matter-antimatter asymmetries on a scale never seen before. Prior to the DZero study, baryon asymmetry and similar CP violations 10 has been observed in laboratory settings only in much smaller—and thus, less helpful—orders of magnitude. This more substantial muon-antimuon asymmetry constitutes the first opportunity for the physicists to study a recurring anomaly of both charge conjugation and parity inversion in a controlled environment. The findings at Fermilab are at once unsettling in that they will soon necessitate a considerable reforming of our understanding of particle physics 11 but titillating in that they may well lead to a more sophisticated and penetrating understanding not only of particle asymmetry but of the nature and origin of the universe itself.

Which choice would provide the most logical connection between the previous sentence and the current sentence?

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