Egg protein is commonly found in which of the following vaccines?

The correct answer is identified as containing egg protein, particularly in the context of vaccines. Influenza and yellow fever vaccines are known to be produced using chicken eggs. When manufacturing these vaccines, the virus is often grown in fertilized chicken eggs, which leads to the presence of egg proteins in the final product.

MMR (measles, mumps, and rubella) vaccine does not typically contain egg proteins in a significant way; however, it can be produced using substrates that could include egg components, which is less common. Despite this nuance, the combination in the chosen answer is the most closely associated with egg protein presence in vaccine production.

Other options do not include influenza or yellow fever, which are specifically linked to egg protein in their manufacturing processes. Hence, while the MMR's association with egg protein might not be as direct as the others, the correct choice emphasizes the relevant vaccines most often connected with egg protein.