
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
In a certain urban district, there are a total of 2,000 households, including 1,800 farmer households, and 100 worker households. A sample of 40 households is to be drawn to survey family income. In the entire sampling process, the following sampling methods can be used: _________. (Fill in the serial number)

1. Simple random sampling; 2. Systematic sampling; 3. Stratified sampling.

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