Respuesta :
im pretty sure that it is d all natural radiation is at a level low enough to be safe
Answer:
Option D
Explanation:
There are three major sources of background natural resources a) Terrestrial Radiation
; b) Internal Radiation and c) Cosmic Radiation
Cosmic Radiation is the radiation received from sun and stars. These radiations are received in traces as they go through different filters such as earth’s atmosphere, its elevation and magnetic field.
Terrestrial Radiations are received from radioactive minerals like uranium, radium and thorium. Since these minerals exists in soil and rock, their exposure is not harmful to mankind
Internal Radiation exists within the body of humans as radioactive potassium-40 and carbon-14 is presents with in the body since birth
Hence, option D is correct