
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
Consider functions $f$ such that $f(x+5) + f(x-5) = f(x)$ for all real $x$. Any such function is periodic, and there is a least positive period $p$ for all of them. Find $p$.
A) 10
B) 15
C) 20
D) 25
E) 30

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