
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 full drum initially contains 100 liters of oil. The drum is drained according to the following rules: On the first day, one fifth of the oil is removed. Each subsequent day, an additional fraction of the remaining oil is removed, such that on the ith day, the fraction removed is \( \frac{i}{i+4} \) of the oil remaining at the beginning of the day. After how many days does the drum contain less than 15 liters of oil remaining?
A) 10 days
B) 11 days
C) 12 days
D) 13 days
E) 14 days

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