Answer:
d. All of the above are true.
Step-by-step explanation:
Being the overall unemployment rate means that it is the "average".
Probably the percentage of unemployment is higher for younger people, like teenagers, and also higher in less educated sectors, like those without a high school diploma.
Probably, the percentage of unemplyment is lower than 8 percent in well-educated sectors like college-educated, middle-aged people.
The total average (rate) makes the 8 percent as a result of all the sectors involved in working ages.