Answer:
Option C
Step-by-step explanation:
Total score for 3 students will be given by the product of average and frequency.
Total score for three students will then be 68*3=204
Similarly, for 4 students, their total score will also be given by
4*75=300
Adding the total score for the two groups
300+204=504
To get the average of all the 7 students, we divide the total score by frequency hence 504/7=72
Therefore, option C is correct
