The most reasonable explanation for the large gap in the histogram is:
c. The histogram includes data from a voluntary response sample which is not representative of the population.
This option suggests that the sample may not accurately reflect the broader population of all drivers in New York City, leading to a potential bias in the data that could create noticeable gaps in the histogram. The inclusion of taxicab drivers (who typically drive much more) alongside residents (who may drive less or not at all) could also contribute to this disparity.