
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
Let $t_n = \frac{n(n+1)}{2}$ be the $n$th triangular number. Calculate the sum:
\[\frac{1}{t_1} + \frac{1}{t_2} + \frac{1}{t_3} + ... + \frac{1}{t_{1001}}\]
A) $\frac{2003}{1002}$
B) $\frac{1001}{501}$
C) $\frac{2004}{1002}$
D) $\frac{1003}{501}$

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