Select the correctly spelled word referring to the environmental process of using biological agents to eliminate contaminants.

The correct option is Bioremediation.

Step-by-step breakdown:

1. Etymology and Definition:
The term is formed by combining two roots:
- "Bio-": A prefix originating from Greek, meaning life or living organisms.
- "Remediation": Coming from the Latin remedium (meaning remedy or cure), which refers to the process of correcting, remedying, or clearing up a problem (in this context, environmental contamination).

2. Correct Spelling Analysis:
Combining these gives Bio + remediation = Bioremediation.
- "Bio-" ends with an 'o'.
- "-remediation" begins with 're-med-i-a-tion' (using 'e' after 'r' and 'e' after 'm').

3. Evaluation of Options:
- Bioremydiation: Incorrectly uses 'y' instead of 'i' in 'diation'.
- Bioremediation: Correct standard spelling.
- Biorimediation: Incorrectly replaces 'e' with 'i' after 'r'.
- Bioremedation: Incorrectly omits the letter 'i' before 'ation'.