Which types of redundancy are necessary for reliable alternatives in an environment of danger which could cause serious losses in case of operational failure?

c. rb

explanation:

the atomic radius of a chemical element is a measure of the size of its atoms, usually the mean or typical distance from the center of the nucleus to the boundary of the surrounding shells of electrons.

frequency or wavelenth of em radiation in a vacuum

where’s the list ? the question is incomplete

wavelength divides in half and speed stays the same.