Final answer:
All the students who went on the field trip could be seniors. Therefore, the answer is D. 24 were seniors.
Step-by-step explanation:
Let's analyze the information given:
The total number of students who went on the field trip is 24.
The total number of seniors in the class is 26.
Since the number of seniors is greater than the total number of students who went on the field trip (26 > 24), it means that all the students who went on the field trip could be seniors. Therefore, the answer is D. 24 were seniors.