Answer: Second option is correct.
Step-by-step explanation:
Since we have given that
Number of sixth graders students = 160
Number of seventh graders students = 180
Number of eighth graders students = 140
If 9 seventh graders were part of a random sample of the population chosen to participate in a survey.
Let Number of sixth graders should be chosen be 'x'.
Since there will be direct proportion .
Hence, Second option is correct.