Final answer:
When organs and tissues do not receive enough blood, they become weak and unable to function properly, which is reflective of the first choice in the provided options.
Step-by-step explanation:
When organs and tissues do not receive enough blood, they become weak and are unable to function properly. This scenario describes Choice 1 from the options provided. The cardiovascular system's role in resource allocation is to ensure that blood flow is redirected to active tissues, as there is not sufficient flow to supply all tissues equally at all times. For instance, during exercise, more blood is directed to skeletal muscles, the heart, and the lungs to match the increased metabolic demand, whereas post-meal, the digestive system receives a heightened supply.
Anemia is one example of what can happen when the blood does not carry enough oxygen due to a lack of red blood cells or hemoglobin. In such cases, the affected organs can suffer damage, experience impaired metabolism, and the overall bodily functions can become threatened.