Which Is More Dangerous in Terms of Short-Lived Exposure to Radiation

Which is more dangerous in terms of short-lived exposure to radiation? One mole of

A) (⁸⁹Sr,β^-,t_1/2 = 50.5 days.)
B) (⁹⁰Sr,β^-,t_1/2 = 28.5 years.)
C) (⁹¹Sr,β^-,t_1/2 = 9.5 hours.)
D) (⁹⁴Sr,β^-,t_1/2 = 74 seconds.)