A wildlife biologist is investigating a sudden increase in the death rate among several bird species. She has not been able to determine what disease or toxin is causing the deaths, but she has found that many of the sick birds are exhibiting a shortage of dissolved oxygen and a buildup of dissolved carbon dioxide in their cells. Which of these body systems in the sick birds is most likely functioning improperly?
Select one:

circulatory and respiratory

reproductive and nervous

muscular and circulatory

excretory and circulatory

blah

explanation: bc blah

c. heat from the poles back down towards the equator.

evidence and logical support is essential for a scientist to do in order to maintain credibility. this is because no one can believe without any logic and without any evidence.hence a scientist can maintain credibility by proving himself and by answering logically so experiments prove very beneficial. logical hypothesis give conclusion which is acceptable. therefore, there are two main factors to maintain credibility by a scientist is evidence and logical support.