
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
Assume $A$, $B$, and $C$ are three propositions. If $A$ is a necessary condition for $B$, and $C$ is a sufficient condition for $B$ but not a necessary condition, then $C$ is a ______ for $A$. (① sufficient but not necessary condition, ② necessary but not sufficient condition, ③ necessary and sufficient condition).

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