Explanation: The photoconductive effect occurs when light strikes a semiconductor material (a crystalline solid). The energy from the photons excites electrons from their bound states, creating free electrons and holes (charge carriers). An increase in the number of these free charge carriers directly enhances the material's ability to conduct electricity. Since conductivity is the reciprocal of resistance, an increase in conductivity means a *decrease* in the material's resistance. This property is fundamental to devices like photoresistors (LDRs) and photodetectors used in various electronic circuits, including those found in radio equipment. The other options are incorrect: * **Capacitance** relates to the ability to store charge, primarily influenced by dielectric material and physical dimensions, not directly by light-induced charge carriers. * **Inductance** relates to magnetic fields produced by current, depending on coil geometry and permeability, not charge carrier density. * **Specific gravity** is a measure of density, a physical property unaffected by light at this level.