
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 keystone arch is composed of 10 congruent isosceles trapezoids, fitted together at the non-parallel sides. If the bottom sides of the trapezoids at either end are horizontal, determine the measure $x$ of the larger interior angle of one trapezoid in degrees.
A) 96º
B) 98º
C) 99º
D) 100º
E) 102º

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