Final answer:
The egg seller's wife believes that the sickness is caused by undercooked eggs. Carli was diagnosed with bacterial gastroenteritis caused by Salmonella bacteria due to undercooked eggs.
Step-by-step explanation:
The egg seller's wife believes that the sickness is caused by undercooked eggs. In the given scenario, Carli's doctor diagnosed her with bacterial gastroenteritis caused by Salmonella bacteria. The eggs Carli had for lunch were undercooked, allowing the bacteria to survive and cause an infection once eaten.