Radioactive decay

is a spontaneous process.

occurs when an unstable nucleus loses energy.

does not require any input of energy.

all of the above

All of the above

Explanation:

Hello,

In this case, since radioactive decay is the spontaneous breakdown of an atomic nucleus resulting in the release of energy and matter from the nucleus, we confirm that it is a spontaneous process as no initiator is required; therefore, no requirement of energy is done and it occurs when an unstable nucleus loses energy.

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Radioactive decay occurs when an unstable nucleus loses energy

So the answer is the second choice