C​‌‍‍‍‌‍‍‌‍‌‌‍‍‍‌‍‌‌‌‍​onsider and comment on how the “three Rs” might be applied to different types of nonclinical studies involving animals. How might they be applica​‌‍‍‍‌‍‍‌‍‌‌‍‍‍‌‍‌‌‌‍​ble in an urgent situation where testing is needed on tests/vaccines/treatments for something like Covid-19? In such a situation, is a waiver appropr​‌‍‍‍‌‍‍‌‍‌‌‍‍‍‌‍‌‌‌‍​iate?