The correct option is D.
Elements undergo chemical reactions because they are not stable and they want to become stable, that is they want to attain octet form. To attain octet form, an atom of element must have eight electrons in its outermost shell. Thus, elements undergo various types of chemical bonding in order to have 8 electrons in their outermost shells.
Neon has atomic number of 10 and its electronic configuration is 2,8. This means that, neon already has 8 electrons in its outermost shell and so does not need to form any chemical bond with any other element again, it is already stable. This is why, neon is the least likely to undergo chemical reaction and this is also the reason whey the element is chemically inert.
The other elements given in the option do not have 8 electrons in their outermost shell, so they will be quite willing to undergo chemical reactions in order to become stable.
