
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 an even function $f(x)$ defined on $\mathbb{R}$ that satisfies $f(x) = f(x + 2)$, and when $x \in [-1, 0]$, $f(x) = 3^x$. Find the value of $f\left(-\frac{15}{2}\right)$.
A) $- \sqrt{3}$
B) $- \frac{\sqrt{3}}{3}$
C) $\frac{\sqrt{3}}{3}$
D) $\sqrt{3}$

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