Final answer:
The most appropriate suggestion for improving the performance of the subgroup of students is defining different academic goals for students who are achieving at different levels or who learn in different ways.
Step-by-step explanation:
The most appropriate suggestion to offer the faculty for improving the performance of the subgroup of students would be Option C: defining different academic goals for students who are achieving at different levels or who learn in different ways. This approach recognizes the diverse needs and learning styles of the students in the subgroup and ensures that each student has goals that are challenging yet attainable. By tailoring the academic goals, teachers can provide more targeted instruction and support to help these students fully benefit from the instruction.