
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
Investigate the possible real values of \( y \) for the list:
\[ 8, 1, 7, 1, y, 1, 9 \]
so that the mean, median, and mode, when ordered in increasing sequence, form a non-constant arithmetic progression.
A) -11
B) 3
C) 17
D) 64

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