Space fire

The above is a comparison between the combustion of a candle on Earth (left) and in a microgravity environment, such as that found on the International Space Station( ISS) (right). That flame shape you're used to can only happen because the fire forces hot air to rise upward. Since none of that really happens in zero gravity, the flame just expands in all directions. Which of the following statements is correct in this context?

a) The convection occurs only at the gravity condition.

b) In zero gravity, the buoyancy does not exist.

c) In zero gravity, the volume of gas is invariant.