TOEFL Listening: TPO-TOEFL阅读TPO - 8RO49908E56347W4N$

It can be inferred from paragraph 2 that tellurium comes before iodine in the periodic table even though tellurium's atomic mass is slightly greater because A. iodine is less common than tellurium B. both iodine and tellurium have no isotopes C. the chemical behavior of tellurium is highly variable D. the atomic number of tellurium is smaller than that of iodine