Although fullerenes--spherical molecules made entirely of carbon--were first found in the laboratory, they have since been found in nature, formed in fissures of the rare mineral shungite. Since laboratory synthesis of fullerenes requires distinctive conditions of temperature and pressure, this discovery should give geologists a test case for evaluating hypotheses about the state of the Earth' s crust at the time these naturally occurring fullerenes were formed. Which of the following, if true, most seriously undermines the argument? ['Some fullerenes have also been found on the remains of a small meteorite that collided with a spacecraft.', 'The naturally occurring fullerenes are arranged in a previously unknown crystalline structure.', 'Confirming that the shungite genuinely contained fullerenes took careful experimentation.', 'Shungite itself is formed only under distinctive conditions.']