A Thermos Keeps a Hot Drink Hot and a Cold

A thermos keeps a hot drink hot and a cold drink cold for a long time. Shown below is a cutaway section of a thermos with the important features labeled. The reason for the silvered double-wall vacuum chamber is

A) the silvered surfaces reflect any radiation while the vacuum suppresses heat losses by convection and heat conductivity.
B) people like silvery things so it is a marketing tool. The vacuum keeps the container clean.
C) the silvered surfaces suppresses heat conduction and convection and the vacuum prevents radiated heat.
D) The vacuum suppresses heat loss by convection, and the silvered material is needed in order to create the vacuum.
E) None of the above.