The Isotope,tritium,has a Half-Life of 12

The isotope,tritium,has a half-life of 12.3 years.Assume we have 10 kg of the substance.What will be the initial decay rate,at t = 0 (in decays/s) ?

A) 1.09 * 10¹⁴
B) 1.8 *10 ^{- 9}
C) 5.6 * 10⁸
D) 3.6 * 10¹⁸
E) 3.6 * 10¹⁷