Final answer:
Marnia attends what is typically called a middle school, which generally serves students in grades fifth through eighth, covering ages approximately 11 to 14.
Step-by-step explanation:
Marnia attends a school with seventh and eighth graders as well as adolescents who are 1 or 2 years younger. This type of educational institution is typically referred to as a middle school in the United States, which serves students in the middle childhood stage. Middle childhood covers the ages of six to ten years and students who are in these grades are beyond this stage and are more independent and physically active than they were in preschool years. They are much more involved with friends and are beginning to think in more complex ways. A middle school usually consists of a combination of grades ranging from fifth through eighth grade, depending on the region, but primarily serves students in the 11 to 14 age range. In contrast, a magnet school is a public school with specialized courses or curricula that draws students from different areas based on their interests. Therefore, the answer to the student's question is a. Middle school.