Final answer:
Impaired circulation and tissue oxygenation lead to an increase in blood lactate concentration due to a higher reliance on anaerobic glycolysis for energy amidst reduced oxygen availability.
Step-by-step explanation:
When circulation and tissue oxygenation are impaired, the blood lactate concentration increases. This is because under low oxygen conditions, cells rely more on anaerobic glycolysis for energy production, which results in the accumulation of lactate. Elevated lactate levels in the blood can be a result of impaired oxygen delivery due to conditions such as anemia, circulatory shock, or heart attacks, where the oxygen-carrying capacity of the blood is reduced or the blood flow itself is insufficient. Therefore, the correct answer to the question is: A) Blood lactate concentration increases.