Explanation:

- The word "contaminating" generally refers to making something impure or dirty by introducing harmful or unwanted substances.

- Option 1: Investing

- This means to allocate resources, usually money, with the expectation of achieving a profit or benefit. Completely unrelated to contamination.

- Option 2: Polluting

- This is the process of introducing contaminants into the natural environment, causing adverse change.

- This synonym effectively aligns with "contaminating."

- Correct Answer

- Option 3: Containing

- This refers to the act of holding or containing something within. Not related to contamination.

- Option 4: Encompassing

- This means to surround or include comprehensively. No direct relation to contamination.