The correct answer is "In prophase I, tetrads of homologous chromosomes form and crossing over occurs".
Explanation:
Mitosis is a type of cell division at which one parent cells produces two daughter cells with identical genomic content and with the same number of chromosomes as the parent. On the other hand, meiosis is a type of cell division at which four daughter cells are produced with half the number of chromosomes respect to the parent cell. The major difference between prophase I of meiosis and prophase of mitosis, is that in prophase I of meiosis, tetrads of homologous chromosomes form and crossing over occurs. The tetrads of chromosomes are the ones that later will make the genomic content of the four daughter cells, while the crossing over is what allows the genetic variations of the sexual cells.