The main reason for making the cover of a vacuum
flask airtight is to prevent heat loss by
A. conduction
B. evaporation
C. radiation
D. convection

(A) conduction

Explanation:

parts of that are touching other parts and thus create heat dont lose that heat!

are you like autistic or something?

xd

there is no correct list among the choices you've provided.

the list might look something like this:

-- baby human

-- piccolo

-- flute

-- soprano singer

-- trumpet

-- tenor singer

-- trombone

-- baritone singer

-- baritone horn

-- bass singer

-- tuba

since i had to make up the list myself, i made it easy on myself, and i didn't try to shuffle the string instruments and woodwinds into it too.