Step 1: Understanding the Concept:
Cleaning effectiveness depends on multiple factors.
These factors are called the cleaning variables.
Step 2: Key Formula or Approach:
No specific formula.
Need to know the cleaning variables.
Step 3: Detailed Explanation:
The process variables determining cleaning effectiveness are:
- Temperature (A)
- Contact time (B)
- Concentration (C)
- Physical action (D)
All four factors are important.
Thus, all statements are correct.
Step 4: Final Answer:
All (A), (B), (C), and (D) are correct.
Hence, the correct option is (C).