
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 $a$, $b$, $c$ satisfy $c < b < a$, and $ac < 0$, which of the following relationships must hold?  
1. $ab > ac$  
2. $c(b - a) < 0$  
3. $cb^2 < ab^2$  
4. $ac(a - c) > 0$.

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