
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
The Fibonacci sequence $1,1,2,3,5,8,13,21,\ldots$ starts with two 1s, and each subsequent term is the sum of its two predecessors. We analyze the sequence obtained by considering the units digit of each Fibonacci number. Determine the length of the shortest repeating cycle in this sequence of units digits.
A) 20
B) 40
C) 60
D) 80
E) 100

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