Answer this will mark brainliest and 3 more times on other questions if you get it right

A

Explanation:

The vaccum keeps the inside of the thermos from losing heat loss

C) It prevents particles from transferring thermal energy between the outer and inner bottles.

If the vacuum portion was filled with air, then the air would help transfer the energy from hot to cold, effectively cooling down the hot liquid inside the thermos. But the lack of air means that the particles can't make such a transfer of energy so the liquid stays hotter for a longer period of time.