Transmutation of an element is the conversion of one chemical element or isotope into another. During transmutation atoms of one element is transformed to atoms of another element or isotope. Transmutation is occurred either via nuclear reactions or radioactive decay.
Melting is the process of transforming a solid into a liquid. The nuclear arrangement of an element is not affected by this. Therefore transmutation doesn't occur.
Nuclear fusion is the process in which the two atomic nuclei join together or as the word suggests they are 'fused' together into heavier elements. Therefore transmutation is happened in fusion.
c. Beta decay
In beta decay, an element is converted into its next highest element. That means atomic number increases via a neutron decays into a proton and an electron. Transmutation occurs in beta decay.
Sublimation is the process in which a solid is transformed into gaseous state (vapor) without going through the liquid phase. One such example is the sublimation of Iodine. Like in melting, the nuclei of atoms are not affected. Therefore transmutation cannot occur.
Nuclear fission is the nuclear reaction or radioactive decay which makes the atoms split into smaller parts. Transmutation occurs during fission.
f. Alpha decay
Alpha decay is the radioactive decay in which an atom decays while emitting an alpha particle or sometimes called as a helium nucleus. The element is converted into a lower element.
Therefore transmutation occurs in b, c, e and f.