
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 first Math Kangaroo test was held in 1991, and it has been given annually. Alex turned 10 years old the year he participated in the ninth Math Kangaroo. In what year was Alex born?
A) 1987
B) 1988
C) 1989
D) 1990
E) 1991

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