Final answer:
The option that will not reduce the probability of contamination from perspiration and saliva of a therapy patient is collecting the patient's waste and storing until decayed to background.
Step-by-step explanation:
The option that will not reduce the probability of contamination from perspiration and saliva of a therapy patient is d. collecting the patient's waste and storing until decayed to background. This method does not provide any barrier or protection against contamination. On the other hand, options a, b, and c (disposable eating utensils, plastic covering over the mattress, and covering the phone receiver with plastic) all provide physical barriers to prevent contamination from perspiration and saliva.