A piece of radioactive material contains 10²⁰ atoms.
If the half life of the material is 20 seconds, the number of disintegration in the first second is

• A.3.47 x 10¹⁸
• B.6.93 x 10 ²⁰
• C.3.47 x 10²⁰
• D.6.93 x 10¹⁸
• E.