I believe that B is the answer.
The silver coating on the inner bottle prevents heat transfer by radiation, and the vacuum between its double wall prevents heat moving by convection. The thinness of the glass walls stops heat entering or leaving the flask by conduction.
Answer:
Copper
Explanation:
Capacitance is directly proportional to dielectric constant
Aluminium and zinc are highly reactive and have high dielectric contact.
Copper has less dielectric constant hence capacitance will decrease
Ruby, a variety of the mineral corundum is in the trigonal crystal system, with hexagonal scalenohedra crystals