
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
In our number system the base is ten. If the base were changed to five, you would count as follows:
\[1, 2, 3, 4, 10, 11, 12, 13, 14, 20, \ldots\]
The twentieth number would be:
**A)** 30_5  
**B)** 40_5  
**C)** 45_5  
**D)** 100_5  
**E)** 50_5

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