Which of the following features is NOT a characteristic of natural radioactivity?

• A.Radioactivity is a nuclear phenomenon
• B.Radioactivity is exhibited only by elements of mass number greater than 206
• C.The radioactivity of an element is affected by electric and magnetic fields in the surroundings
• D.Radioactive substances emits three types of radiations, a-rays, \(\beta\)-rays and y-rays
• E.The radioactive element is transformed into a new element