Final answer:
The valid conclusion from the benchmark test results showing 15 percent of students at Sunshine Middle School are below grade level in mathematics is that the school district should offer additional support to these students.
Step-by-step explanation:
Based on the data that 15 percent of the students at Sunshine Middle School were below grade level in mathematics, the conclusion that is valid is : (D) The school district should provide additional support to students at Sunshine Middle School who are below grade level in mathematics.
This conclusion is driven by recognizing that there may be a need for further assistance to improve student performance, rather than attributing the low scores to the intelligence of the students, the ineffectiveness of the entire mathematics program, or the validity of the benchmark test itself.
It is important to use benchmark test results to identify areas where students can benefit from additional support, potentially addressing the issues highlighted in TIMSS or high school exit exams, which indicate that there is room for improvement in mathematics education.