Which choice most logically completes the text?

Source Texts

Text

Paleoanthropologists have struggled to determine the onset of consistent clothing use by hominids. The appearance of hide-scraping tools by 780,000 years ago (780 Ka) enabled clothing production but does not entail it, and while clothing is thought to have been thermally superfluous for anatomically modern humans in their African range around their emergence by 300 Ka, it was essential for the persistence of humans outside Africa by 70 Ka. Melissa Toups et al. proposed a novel proxy: the evolution of the clothing-exclusive variant of the human-exclusive parasite Pediculus humanus (head lice), which Toups et al. date to as early as 170 Ka. This variant could not have emerged and survived without ample ecological niches, so if Toups et al. are correct, then ________

it is unlikely that hominids other than anatomically modern humans produced or wore clothing even though tools enabling the production of clothing existed well before the emergence of humans.

humans most likely began regularly wearing clothing at some point after 170 Ka but before approximately 70 Ka.

a substantial proportion of humans must have regularly worn clothing long before humans permanently inhabited areas cold enough to necessitate doing so.

the spread of regular clothing use among humans after approximately 70 Ka may have been motivated by factors other than the thermal benefits that clothing provides.