Someone me sort these out for either if they are heterogenous, solution, suspension, or colloid. tuna casserole, green salad, gelatin dessert, apple juice, oil and vinegar salad dressing, and chocolate chip cookies

Heterogeneous-a mixture of two or more things
solution-a substance that dissolves
suspension-mixture where solid particles do not dissolve
colloid-does not settle and cannot be seperated

Heterogeneous
- tuna casserole
-chocolate chip cookies
-gelatin dessert
-green salad
Solution
-oil (?) depends 
Suspension
-vinegar salad dressing
-oil (?) it could go in either catagory
Colloid
-vinegar salad dressing
-oil (?)

Ido not understand.