Answer: Norm-referenced grading
Explanation: Norm-referenced grading system is the grading technique in which the comparison is made between a particular person and the norm group based on their knowledge. The norm group is made on the basis of assessment or tests who act as the representative in regard with other people or students. .
The grading system that should be used by Mrs. Ramirez for the choosing the top three or four students should be made by norm based grading pattern which can bring out the top students by giving the test or exam for assessment .