Most of the earth's volume is contained in the
a. mantle
b.
crust
c.
inner core
d.
outer core

answer:

its a

explanation:

this region is known as the mantle, and accounts for the vast majority of the earth's volume. movement, or convection, in this layer is also responsible for all of earth's volcanic and seismic activity

the correct answer is (d) the pilot can increase the temperature inside the balloon so it is warmer than the surrounding air.

this is based on the phenomenon that warm air rises up so the pilot should increase the temperature inside the balloon as compared to the surrounding air. this will rise the balloon up. the hot air will make the balloon   go up fastly.