Explanation

A detachable cofactor made of an inorganic ion is generally called a metal ion or sometimes just part of the broader 'cofactor' category. However, among the choices, Coenzyme (B) refers to organic cofactors, and Prosthetic group (A) are tightly bound groups. Given the options and definition, the term for a detachable inorganic ion cofactor is often simply referred to as an inorganic cofactor or metal ion, but if forced to choose from standard biochemical terms, 'Cofactor' itself (D) is the general term, while 'Coenzyme' usually implies organic molecules.