Final answer:
The second sector does not have the lowest average test scores.
Step-by-step explanation:
In the double bar plot, we can see that the second sector does not have the lowest average test scores. This means that option (a) is true. The second sector might not have the highest average test scores, so option (b) might be false. We cannot determine the width of the interquartile range from the double bar plot alone, so option (c) is uncertain. Lastly, we cannot determine the number of students in each sector from the double bar plot, so option (d) is not supported by the given information. Therefore, the correct answer is option (a) - The second sector does not have the lowest average test scores.