
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
For every $n$ the sum of $n$ terms of an arithmetic progression is $S_n = 5n + 4n^2 + 1$. Find an expression for the $r$th term.
- **A)** $8r$
- **B)** $8r + 1$
- **C)** $8r - 1$
- **D)** $9r$

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