Final answer:
Pathogenic foodborne bacteria are typically neutrophiles that grow best at a neutral pH close to 7, so the correct answer to the question is C. 7.
Step-by-step explanation:
Pathogenic foodborne bacteria grow best at a neutral pH close to 7. Neutrophiles such as Escherichia coli, staphylococci, and Salmonella spp. prefer this pH range. According to the given information, most familiar bacteria do not thrive in highly acidic conditions, like those of the stomach. However, certain pathogenic strains are more resistant. Fungi, contrasting bacteria, favor slightly acidic conditions with an optimum growth pH between 5.0 and 6.0.
Lactic acid bacteria used in fermenting yogurt and other acidic foods can thrive at a pH close to 4.0. Conversely, alkaliphiles, which represent another group of organisms, grow best in pH conditions ranging from 8.0 to 10.5. It's important to distinguish between neutrophilic bacteria that grow best near neutral pH and pathogens like Lactobacillus acidophilus that prefer more acidic environments and vibrio cholerae which favor slightly basic conditions.
Considering this information, pathogenic foodborne bacteria will have an optimal growth pH near the neutral point. Therefore, the correct answer to the question about the pH value at which pathogenic foodborne bacteria grow best is C. 7.