plastic wrap is transparent which makes heat come through the glass and makes it hotter
[the reason metal is cold is because when you touch it ,it absorbs your heat energy and it feels cold].
Plastic wrap is what keeps things colder because its surface is very dense which means it can absorb more heat more easier than metal
so the answer is aluminum foil
Aluminum foil is denser than plastic wrap and I think it's a type of metal, which sorta absorbs more cold air from the fridge which keeps the item colder.
Plastic wrap is great to keep food fresh, though!
I think that aluminium foil would be more effective in keeping something cold because:
1. It is thicker. Thickness makes it harder for the outside temperature to penetrate and influence the temperature of the thing.
2. It is made of metal. Metal is a material that holds temperature. It slowly becomes room temperature, while plastic just loses heat/cold.
Aluminum foil definetly!