Final answer:
Toppings on burgers and sandwiches depend on the establishment's practice, but the example of a ham sandwich lacking lettuce and onion suggests these might not come standard. In comparison, the digestion of a sandwich is a complex process where food is mechanically and chemically broken down along the digestive tract.
Step-by-step explanation:
If you are asking about toppings that typically come with burgers and sandwiches at a restaurant or in a general sense, it is essential to note that there isn't a universal standard as it varies by establishment. However, the scenario provided here does not specify if lettuce, tomato, and onion are included automatically.
Considering the details given on the composition of the ham sandwich - with ham, cheese, tomato, pickles, and bread - it suggests that, at least for this particular sandwich, lettuce and onion are not included. Therefore, if this pattern followed by the ham sandwich is reflective of other sandwiches and burgers at the same place, then toppings like lettuce and onion might not be included by default.
Relating to the question about the digestive system, the digestive process of a bacon, lettuce, and tomato sandwich involves a complex system that works similarly to a conveyor belt in a factory.
Food is broken down through mechanical and chemical means as it moves through the digestive tract, from the mouth where it is chewed and mixed with saliva, all the way to the stomach and intestines where it is further digested and nutrients are absorbed, until waste is eventually excreted.
The correct option is d) No, they come plain and guests can request toppings.