Final answer:
Vinegar has more hydrogen ions than milk due to its lower pH value.
Step-by-step explanation:
The number of hydrogen ions in vinegar and milk can be determined based on their pH values. Vinegar has a pH of about 2.0, while milk has a pH of around 6.5-6.7. The pH scale is logarithmic, which means that each whole number increase or decrease in pH represents a tenfold difference in hydrogen ion concentration. Therefore, vinegar has a higher concentration of hydrogen ions compared to milk, making Option B: More in vinegar, the correct answer.