
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
A teacher gives you a sequence of numbers from 1 to 15. She asks you to find out which single number must be removed such that the average of the remaining numbers is $7.5$.
A) 14  
B) 13  
C) 12  
D) 15

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