A sample of calcium carbonate weighs 2.1 kilograms (kg). There are 1,000 grams (g) in 1 kg, and 1 Times. 109 nanograms (ng) in 1 g.What is the mass of this sample in ng?

2.1 x 10⁶ ng
2.1 x 10⁹ ng
2.1 x 10¹² ng
2.1 x 10³ ng