Thanks for a question in another one of my favourite topics evolution. The strongest evidence for me would be the fact that all living things share the very basic unit of life, genes, and basic structural units, cells. This suggest that all living things came from a common ancestor whose basic structural unit was a cell and who passed down information through genes. Another striking point is observing similar organs or structures in animals that are not closely related. E.g. the wing of a bird, the front limb of a frog and the arm of a man all have similar structure suggesting similar origin. Therefore all these animals came from a common ancestor who had limbs. The other evidence lies in fossil records which have revealed very strange creatures who might have been intermediates of different animals we see today. Remember evolution is slow and can take millions of years which makes it very difficult to observe within our lifetimes.