A Nuclear Explosion Produces (Among a Lot of Other Things)7 $\times$

A nuclear explosion produces (among a lot of other things) 7.9 $\times$ 10²³ Bq of iodine-131,which has a half-life of 8.05 d,and 5.7 $\times$ 10²¹ Bq of barium-140,which has a half-life of 12.8 d.The total activity that remains after 145 d is

A) 3.5 $\times$ 10¹⁸ Bq
B) 1.16 $\times$ 10²⁰ Bq
C) 2.2 $\times$ 10¹⁸ Bq
D) 5.2 $\times$ 10¹⁸ Bq
E) 7.3 $\times$ 10¹⁸ Bq