Answer:
A) The bowling ball will hit the ground first. It is heavier, which has greater density, allowing it to reach the ground first.
B) Feather. If you want to be able to blow a bowling ball in a vaccum cleaner, it's almost impossible since it's very heavy. If it's a feather, it would be easier as it's light and the air inside it is able to force it down.
Note: I haven't learnt physics at all yet, this is just an attempt. I'm in 7th grade currently and I will probably be taking physics sometime in 9th grade.