[Q]: Which of the following solutions is better for the following goal:
How to create an anti-allergen vacuum cleaner.

[A]: First decide if you want to make a bag, or bag-less model, then decide if you want to make an upright or cannister model, finally consider what type of allergens you wish to block and address those through appropriate filtering devices.

[Q]: Which of the following solutions is better for the following goal:
To make Mario Bros coins to lay around your room,

[A]: take regular coins and spray paint them bright yellow.

[Q]: Which of the following solutions is better for the following goal:
get batter ready to bake

[A]: Add the batter to a piping bag with a large star piping nozzle and pipe onto a tray with non stick spray applied to it.

[Q]: Which of the following solutions is better for the following goal:
How to fix a belt hanger in the closet?

[A]:
Fix a strong yet slim wooden or metallic rod horizontally in one of the compartments of the closet.