For the stone collectors on the ancient lakeshore terraces on the southeastern shore of Selincuo in northern Tibet, the researchers believe that these stone tools show a strong European middle-aged cultural style of Paleolithic in terms of production technology and typology, and use the European typical "Quena trimming method" during processing. The "thinning" technology, it is believed that the approximate age of the Serin Woolstones maybe around 40,000 to 30,000 years ago. Which of the following, if true, would most weaken the conclusion? ['European Paleolithic cultural style is relatively unitary and lacks change.', 'Typical "Quena trimming method" in Europe is the main method of stone processing.', 'Later research encountered obstacles in the identification of some stone cultural styles and processing techniques.', 'Stone tools similar to those collected from the ancient muddy terraces on the southeastern shore of Serincuo in northern Tibet were found elsewhere.']