Answer:
Smoke
Explanation:
All of those listed are under the group of matter, except for smoke, making it the odd one one.
The rough definition of matter means that it occupies space, but smoke does not.
There are 3 main groups, Solid, Liquid and Gas.
Milk is classified under liquid.
Carbon Dioxide is classified under gas.
Butter is classified under solid.
Since you cannot classify smoke under any of the 3 categories, it is the odd one out.
