In the heart and groundbreaking work of Otto Loewi, the heart of a donor frog was stimulated to beat more rapidly than the normal basal rate. When an extract of fluid from the donor frog's heart was administered to the heart of a recipient frog, its heart rate also accelerated. Loewi concluded that :

humans, along with other animals and plants, have linear chromosomes that are arranged in pairs within the nucleus of the cell. the only human cells that do not contain pairs of chromosomes are reproductive cells, or gametes, which carry just one copy of each chromosome.

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.

i think it is d. objects resist changes in their state of motion.