Tritium Is Radioactive with a Half-Life of 12

Tritium is radioactive with a half-life of 12.33 years decaying into ³He with low-energy electron emission.If we have a sample of 2.35 × 10¹⁹ tritium atoms,what is its activity in decays/second? (1 year = 3.16 × 10⁷ s)

A) 6.64 × 10⁷/second
B) 5.35 × 10⁹ /second
C) 3.69 × 10⁸/second
D) 4.18 × 10¹⁰/second