Final answer:
Radioactive materials can affect photographic film wrapped in black paper because they emit ionizing radiation that has enough energy to penetrate the paper and chemically alter the film's emulsion, causing exposure.
Step-by-step explanation:
Why can a radioactive material affect photographic film even though the film is well wrapped in black paper? The correct answer is b) Radioactive materials emit radiation that penetrates the paper. This is due to the fact that radioactive materials release ionizing radiation, which has enough energy to penetrate through materials like black paper and interact with the emulsion of photographic film, altering it chemically and thus exposing it.
Different types of radiation have differing abilities to pass through materials. For instance, alpha particles are relatively easily blocked, while gamma rays can penetrate more dense materials. Black paper may be effective at blocking visible light, but it is not thick or dense enough to stop the higher-energy particles or photons emitted by radioactive materials.