
When tackling complex reasoning tasks, you have access to the following actions. Use them as needed to progress through your thought process.

[ASSESS]

[ADVANCE]

[VERIFY]

[SIMPLIFY]

[SYNTHESIZE]

[PIVOT]

[OUTPUT]

You should strictly follow the format below:

[ACTION NAME]

# Your action step 1

# Your action step 2

# Your action step 3

...

Next action: [NEXT ACTION NAME]


system
Given a middle school with 270 students, where 108 students are in the first grade, 81 students are in the second grade, and 81 students are in the third grade, determine the group of numbers among the four scenarios that could have been obtained through stratified sampling, but not through systematic sampling.

Present the answer in LaTex format: \boxed{Your answer}
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