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

Multiple Choice

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

A) .⁸³Sr,?^-,t_1/2 = 1.35 days.
B) .⁹⁰Sr,?^-,t_1/2 = 28.5 years.
C) .⁸⁰Sr,?^-,t_1/2 = 1.77 hours.
D) .⁹⁴Sr,?^-,t_1/2 = 74 seconds.