a vacuum flask keeps its contents warmer or cooler than the surrounding environment for a length of
time. it consists of two flasks, one inside the other, that connect at the neck. the space between the two
flasks is completely empty of air.

q-why does the design of the vacuum flask minimize heat transfer by conduction?

a)- one flask is smaller than the other flask.
b)- one flask is more reflective than the other flask.
c)- there is no air between the two flasks.
d)- the two flasks do not touch each other, except at the neck.