
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
If $n$ is a multiple of $8$, consider the sum $s = 1 - 2i + 3i^2 - 4i^3 + \cdots + (n+1)(-i)^n$ where $i = \sqrt{-1}$. Calculate the value of $s$.
**A)** $1.5n + 1$  
**B)** $1.5n$  
**C)** $1.5n + 1 - 0.25ni$  
**D)** $n - 0.25ni$

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