Final answer:
Hypovolemic shock results in a decreased circulating blood volume, leading to decreased tissue perfusion with oxygen.
Step-by-step explanation:
In hypovolemic shock, there is a decrease in the circulating blood volume -- this decreases tissue perfusion with oxygen. Therefore, the correct answer is a) Decrease, blood, decreases, oxygen. Hypovolemic shock is a type of circulatory shock caused by an excessive loss of blood volume, which can result from hemorrhage or conditions like severe dehydration. This loss results in reduced oxygenation of tissues, as the diminished blood volume lowers the efficiency of oxygen delivery to cells throughout the body. In hypovolemic shock, there is a decrease in the circulating blood volume -- this decreases tissue perfusion with oxygen.