Explain why sexual reproduction is a source of genetic variation

Three events in sexual reproduction that contribute to genetic variation include crossing over, in which the sister homologous chromosomes of a cell exchange genetic material through recombination of genes. Another event is independent assortment or random fertilization, as there are numerous variety of ways that the chromosomes of the gametes can combine, after meiosis, through fertilization to form a zygote. The third is mutation, in which on rare occasion, there is a slight and random change in the genes of a gametic cell caused by environmental factors.

hey bro i looked it up on google the structure of the eye-spot in euglena viridie, e. ehrenbergii, and phacus pyriyorme is not as franzé haa described it. the so-called “crystal body” and “lens bodies” were not found in any of the individuals of the species examined by me. as earlier observers have stated, the eye-spot consists simply of a mass of pigment granules arranged in a single layer, and probably embedded in a protoplasmic framework, but the latter could not be seen, and its presence was only inferred from the fact that the pigment granules must be held together in some way, thd the eye-spot as a whole is capable of expansion, and that the pigment granules can be separated from each other.

hope this   and an i get brainlsiest

b. lithosphere, asthenosphere, mesosphere   is the answer most likely