Can we make a universal rule regarding spontaneity of reaction based on the energy change of a system?

if gibbs free energy change is negative then the reaction is spontaneous

it is to be noted that an alpha particle is an helium nucleus. so it contains 2 protons 2 neutrons and has a mass number of 4. when alpha decay particles are ejected from the nucleus it gets transformed into an atom which has atomic number less than 2 and a mass number less than 4.

an equation that could represent alpha decay is radium 226 decay of alpha particle forms radon 222.

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the answer is option a.