Final answer:
Approximately c. 15% of the school-age population consists of students with disabilities in special education.
Step-by-step explanation:
The best estimate for the percentage of the school-age population consisting of students with disabilities in special education is approximately 15% (option c).
According to the National Center for Education Statistics (NCES), students with disabilities graduate from high school at a national average of about 73%, which is lower than the average graduation rate for students in all populations (88%). However, there are still disparities in services and support for students from lower-income areas and states with lower education budgets.
In summary, approximately 15% of the school-age population consists of students with disabilities in special education.