Plzzz need help going to faiel

just finished the test, the answer is d, greg is the least cost-effective because he charges the most for the project

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.

im not intirely sure but i think the anwser is d relative humidity