Final answer:
The waiting time for organ transplants is buffered by time.
Step-by-step explanation:
The correct answer is A. Time.
In organ transplant systems, waiting times are often very long due to a scarcity of available organs. The variability in waiting times is buffered by time, meaning that the longer a patient waits, the greater the chance of receiving a transplant. Time allows for more opportunities for suitable donors to become available and increase the chances of finding a match.
For example, a study by Dipchand et al. (American Journal of Transplantation, 2010) compared the survival rates for infants receiving donor hearts that were ABO compatible and incompatible. The waiting time for a suitable donor heart was critical because the patient's health could deteriorate during the waiting period. Therefore, time plays a crucial role in buffering the variability in organ transplant systems.