There isn't really a right answer to this, it's more opinion based. What did you cover in class? If its relating to foodborne illness and sanitation then you could say, "One fact that I thought was most important was to avoid cross contamination with certain foods like poultry or raw eggs"
All of the above. At least that would be my response
Commas are used when two independent clauses are joined with coordinating conjunctions (For, And, Nor, But, Or, Yet, So).
Example: I wanted to play cricket, but I was not feeling well.
However, there are always exceptions to this.
Hope this helps:)
