Unfortunately, there seems to be a missing piece of information here, as the stem-and-leaf plot data has not been provided for analysis. Solving this question accurately requires that data.
However, if the stem-and-leaf-plot data were provided, we could solve it like this:
A stem-and-leaf plot shows data values grouped, where each group (the "leaf") represents a certain range, and the values in that group (the "stem") are individual data points within that range.
To answer this question, we would find the 'leaf' or group that represents 4.0 kilometers in the stem-and-leaf plot. We would then count the number of 'stems,' or individual data points, within that group. This would give us the number of students traveling approximately 4.0 kilometers to school.
That number would be the most accurate estimate for the solution to the problem.
We would then look at the given multiple choice options (a, b, c, d) and select the one that is the closest match to our calculated result. Without the specific data available, it is not possible to provide a definitive answer at this moment.