Answer: c. Salmonella
Salmonella is a strain of bacteria that lives in the intestines of birds, humans and animals. These bacteria can contaminate raw food and water because of feces released by these organisms. During the egg formation, the Salmonella bacteria is transferred inside the egg before the egg is covered by the external hard shell in birds. The eggs can also be contaminated externally due to release of feces by these birds.
Therefore, it is required to boil the eggs before they are consumed to kill these bacteria. Hence, consuming eggs that aren't cooked enough can lead to infection with Salmonella.