Final answer:
Signs of rodent infestation include grease marks, signs of gnawing, and feces that look like grains of black pepper, but paper scraps alone are not a definitive indicator.
Step-by-step explanation:
Signs of a rodent infestation include grease marks under doorways or around holes in buildings, signs of gnawing on materials such as wood or plastic, and grains of black pepper looking feces which are typical of rodent droppings. However, option c) Paper scraps is not typically a sign of rodent infestation. While rodents can create nests from paper scraps, the presence of scraps alone without other signs is not a definitive indicator of an infestation.