**Core Concept:** Meiosis is a type of cell division that produces gametes (sex cells) in sexually reproducing organisms. In meiosis I, one division occurs with double reduction, where homologous chromosomes pair and exchange genetic material through crossing over. In meiosis II, the chromosomes separate and the cell produces 4 genetically unique haploid cells. Non-homologous chromosomes do not pair and recombine, leading to random assortment of genes and genetic diversity.

**Why the Correct Answer is Right:** During meiosis I, homologous chromosomes pair up and undergo crossing over, allowing for genetic recombination between non-identical chromosomes. This process is crucial for genetic diversity and adaptation in living organisms. The correct answer (C) refers to the correct process of genetic exchange between non-homologous chromosomes during meiosis I.

**Why Each Wrong Option is Incorrect:** Option A is incorrect as it refers to homologous chromosomes pairing and crossing over, which occurs between homologous chromosomes, not non-homologous chromosomes. Option B discusses homologous chromosomes recombining, which is not the correct process for non-homologous chromosomes. Option D is also incorrect as it discusses homologous chromosomes pairing and crossing over, which does not occur between non-homologous chromosomes.

**Clinical Pearl:** Meiosis ensures genetic diversity through random assortment of genes, which is essential for adaptation and survival of species. Understanding meiosis and its mechanisms is crucial for medical students, as it has implications in fields like genetics, reproductive biology, and inherited diseases.

**Correct Answer:** C. Non-homologous chromosomes undergo crossing over during meiosis I to generate genetic diversity.