How Many Radioactive Atoms Are Present in a Sample That $\mu$

How many radioactive atoms are present in a sample that has an activity of 0.5 $\mu$ Ci and a half-life of 10 years? (1 curie = 3.7 * 10¹⁰ decays/s)

A) 9.5 * 10¹² atoms
B) 8.4 *10¹² atoms
C) 7.3 * 10¹² atoms
D) 6.5* 10¹² atoms
E) 2.7 *10⁵ atoms