The correct answer is "cleaning the plate used to carry the chicken to the grill with a paper towel before using it for serving raw vegetables".
Trevor should be careful and should perform all of the other available choices in order to avoid cross contamination. He should wash his hands before and after touching the chicken, to avoid transferring any pathogens to the chicken or from the chicken to the rest of the food products using. The same applies for sanitizing the knife. Grilling the chicken in the appropriate temperature will kill any dangerous pathogens and ensure that the consumer of the chicken will be safe.
Cleaning the plate with a paper towel will not sanitize or kill any pathogens. Also raw vegetables should not be served on this plate, since pathogens can be transmitted to the raw vegetables.