Answer: Keith and Aaron only
Step-by-step explanation:
Since the school record for the 100-meter dash is 18 seconds, while
Juan did 19 seconds;
Hans did 16 seconds;
Keith did 17 seconds; and
Aaron did ILELE (unknown value)
Based on this illustration, only Keith and Aaron finished the 100-meter race at a lesser time than the school record.
Thus, Keith and Aaron only are the students that have broken the school record.