What is the carcinogenic label for bond TR001_2_4?
label = '+' mean molecules are carcinogenic
SELECT DISTINCT T2.label FROM atom AS T1 INNER JOIN molecule AS T2 ON T1.molecule_id = T2.molecule_id INNER JOIN bond AS T3 ON T2.molecule_id = T3.molecule_id WHERE T3.bond_id = 'TR001_2_4'