An idea that the universe originated with an explosion is supported by repeated observations of light from distant galaxies traveling away from Earth. An idea that has been tested repeatedly and is supported by repeated results is MOST likely a

the answer is 1. photosynthesis. glad to

genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).

several tissues working together form an organ, and several organs together make up an organisms.

the group of cell that carries out special jobs are tissue.

the sun creates it's own light, also gives light and life to bunch of stuff like plants,animals,humans etc.photosyntesis is the process of making food which needs sun,water,nutrients etc.