Answer: crossing over and random orientation of homologous pairs.
Step-by-step explanation:
Two factors during meiosis I :
Chromosomal crossover in meiosis prophase I. The DNA is broken on each homologue and reconnected in a criss-cross pattern so that homologues exchange part of their DNA. This process is called crossing over.
Random orientation of homologous pairs in meiosis metaphase I. When the homologous pairs line up, the orientation of each pair is random.
This allows for the formation of gametes with different sets of homologues.
Spymore