Final answer:
Without the actual bar graph or additional information about the dataset's distribution, we cannot determine the relationship between the mean and median; hence the correct answer is D. There is not enough information to compare the mean and the median.
Step-by-step explanation:
When considering the relationship between the mean and median in a dataset, it is crucial to understand how the skewness of the data can affect these measures of central tendency. For a symmetrical distribution, the mean, median, and mode all coincide at the same point. However, in a skewed distribution, these measures typically differ. If the data is skewed to the right, the mean will be greater than the median. If the dataset is skewed to the left, the median will be greater than the mean.
To answer the student's question accurately, one would need to see the actual bar graph mentioned. Without the visual data or additional information about the distribution, it is impossible to determine whether the mean is greater than the median, the median is greater than the mean, or if they are equal. Therefore, the correct answer is D. There is not enough information to compare the mean and the median.