How can a technician assess a client's suitability for eyelash extensions?

The correct choice emphasizes the importance of conducting a patch test for adhesives if allergies are suspected, ensuring the client's safety and comfort during the application process. This assessment is crucial because some clients may have sensitivities or allergic reactions to certain ingredients found in eyelash extension adhesives. Conducting a patch test helps to identify any potential allergies before proceeding with the full application, minimizing the risk of unwanted reactions such as redness, irritation, or more severe allergic responses.

Other options, such as reviewing a client’s makeup routine, evaluating their social media presence, or asking about recent travel history, do not directly address the potential health risks associated with eyelash extensions. While these factors might provide some context about a client's lifestyle or preferences, they do not serve as effective methods for assessing the suitability of the client regarding potential allergic reactions to adhesives used in the lash extension process. Thus, the patch test stands out as the most vital step in ensuring a safe and positive experience for the client.