Question

what would be the main problem with reproduction if meiosis did not take place to form sex cells?
the zygote would have two nuclei.
fertilization would result in a zygote with half as many chromosomes as the parents.
fertilization would result in a zygote with twice as many chromosomes as the parents.
the zygote would have no nucleus.

Explanation:

Meiosis reduces the chromosome number by half in sex cells (gametes). If meiosis didn't occur, gametes would have the same chromosome number as somatic cells. When fertilization happens (sperm + egg), the zygote would have double the normal chromosome number (since each parent contributes a full - set instead of a half - set). A zygote with two nuclei is incorrect as normal fertilization fuses nuclei. A zygote with half the chromosomes (compared to parents) would be if gametes had more reduction (but normal meiosis already halves, not more). A zygote with no nucleus is not related to the absence of meiosis in this context.

Answer:

Fertilization would result in a zygote with twice as many chromosomes as the parents.