Always go to a low gear when going downhill, keep the rule that if you go uphill, you will go downhill by that number.
Answer 1 is wrong because increasing to a high number, answer 3 is wrong because to zero
Increase to a high gear, release the gas pedal at an appropriate level, combined with the foot brake to control the speed.
In low gear, release the accelerator pedal at an appropriate level, combined with the foot brake to control the speed.
To zero (0), release the accelerator pedal to an appropriate level, combined with the foot brake to control the speed.