Double-paned windows are made of multiple layers of glass with gas trapped between them. these offer than single-paned windows and can make a house more energy efficient. aconduction  binsulation  cconvection  dcondensation

Conduction and convection are names given to the modes of heat transfer. To prevent the transfer of heat from one system to another we use insulation between the contact surface of the systems. Double-paned windows are made of multiple layers of glass with gas trapped between them and hence has better insulation than single-paned windows. Condensation is the name given to the conversion of a vapor or gas to a liquid. Thus the correct choice is

(B) Insulation