3. Potatoes
Botulism can grow on potatoes, especially if sealed in foil. The problem with reheated potatoes is not the reheating but how you store the potatoes after they are cooked.
If they are left to cool at room temperature (and then left unrefrigerated), conditions may be right for growth of Clostridium botulinum (botulism), especially if they are sealed in foil so that oxygen is kept out of the potato.
Reheating the potato will not always kill these off, so storing potatoes safely as they cool is sensible.