
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 university has 200 students and 4 professors. During a certain period, each student attends one class, and each professor teaches one class. The class sizes are 100, 50, 30, and 20 students. Determine $t - s$, where $t$ is the average number of students in a class when a professor is randomly chosen, and $s$ is the average number of students in a class when a student is randomly chosen.
**A)** -25
**B)** -19
**C)** 0
**D)** 19
**E)** 25

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