The photo shows an old-fashloned mercury thermometer. Mercury is a liquid metal that expands when It Is heated. Mercury Narrow tube Bulb with thin glass covering Which statement best describes how the thermometer's bulb works?

A. The thin glass covering transfers thermal energy to the mercury so it can start to expand sooner.
B. The mercury easily transfers thermal energy so the thin glass covering can start to expand, C. The thin glass covering reflects thermal energy to stop the mercury from expanding, D. The mercury reflects thermal energy so the speed of energy transfer through the glass happens quickly.​