Question

The passage discusses a scientific debate regarding the detection of phosphine on Venus. Read the passage and match each argument or piece of evidence on the left with the statement on the right that best evaluates its logical strength or credibility.

Passage

In 2020, a team of astronomers announced the detection of phosphine gas ($PH_3$) in the temperate clouds of Venus using the James Clerk Maxwell Telescope (JCMT) and the Atacama Large Millimeter/submillimeter Array (ALMA). Because phosphine on Earth is a well-known biomarker associated with anaerobic organisms, the researchers cautiously suggested that the gas could indicate extraterrestrial microbial life.

However, this argument faced immediate scrutiny. Dr. Sarah Jenkins, an atmospheric chemist, pointed out that the $267\text{ GHz}$ spectral line used to identify phosphine overlaps almost perfectly with a spectral line for sulfur dioxide ($SO_2$), a common volcanic gas on Venus. Jenkins argued that the initial analysis misidentified $SO_2$ as $PH_3$, thereby invalidating the primary evidence for the biomarker claim. To support her critique, Jenkins simulated Venus's mesospheric chemistry, showing that volcanic plumes could easily produce the observed spectral signature at $267\text{ GHz}$ without requiring any phosphine.

In response, the original discovery team released a re-analysis of their ALMA data. They argued that while $SO_2$ contamination was possible, the sheer absorption line depth they recorded could not be accounted for by $SO_2$ alone under known Venusian atmospheric conditions. They cited independent data from the Pioneer Venus Large Probe mass spectrometer (which detected phosphorus-bearing compounds in 1978) to bolster the credibility of their phosphine identification. However, critics like Jenkins note that the 1978 probe data was highly localized and has a margin of error wide enough to include simple phosphoric acids, which are not biomarkers.