One of the Radioactive Isotopes That Fell on the Land

Multiple Choice

One of the radioactive isotopes that fell on the land and got into the food chain after the Chernobyl accident was ¹³¹I. Its half- life is 8 days. How long was it, following its deposit on the land, before its radioactivity had fallen to 1/32-- about 3%-- of its initial value?

A) 48 days
B) 40 days
C) several years
D) 16 days
E) It is impossible to say, even approximately.