To determine which pair of words the word-formation process of Backformation can apply to, we need to understand the meaning of backformation. Backformation is a process in which a new word is formed by removing an actual or supposed affix from another word in the language. This process usually involves removing a suffix to create a new word, often a verb.

Let's analyze the given pairs:

• laser, scavenger: "Laser" is an acronym (Light Amplification by Stimulated Emission of Radiation) and "scavenger" is a noun derived from "scavenge." The process of backformation can be applied here as "scavenge" can be derived by removing the "-er" suffix from "scavenger."
• kudos, laser: Both "kudos" and "laser" do not fit the backformation criteria as "kudos" is an original noun, and "laser" is an acronym.
• scavenger, emotion: "Scavenger" forms "scavenge" by removing the "-er," which is an example of backformation. However, "emotion" is not derived through backformation, as it doesn't serve this etymological process.
• emotion, kudos: Both "emotion" and "kudos" do not undergo backformation. They are lexical items derived from different roots or processes.

Now, focusing further on the pairs, "scavenger, emotion" is included because "scavenger" can produce "scavenge" through backformation. Thus, the correct pair for a backformation is "scavenger, emotion."