Which of the following most logically completes the argument?THE 17th-century frescoes in Valencia's Santos Juanes Church were damaged when the church burned and then a restoration effort in the 1960s left glue residue on the art, and nitrates from the droppings of pigeons roosting behind the walls migrated through to the surface, leaving a white buildup. Therefore, the planned introduction of bacteria that were trained in a lab to eat certain types of organic matter would be a good way to clean the artworks, since