
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
Consider a rectangle where the lengths of adjacent sides are in arithmetic progression. If the shorter side is $a$ units and the progression's common difference is $d$ units, find the area, $K$, of the rectangle.
A) $a^2$  
B) $a^2 + d^2$  
C) $a^2 + ad$  
D) $2a + d$

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