Final answer:
Parents produce offspring with new combinations of phenotypes through both crossing over during meiosis and without crossing over, thanks to processes such as independent assortment and random fertilization.
Step-by-step explanation:
Parents can produce offspring with new combinations of phenotypes through both crossing over and without crossing over. Crossing over is a key mechanism that contributes to the genetic variation among offspring. During meiosis, specifically in prophase I, crossing over occurs where genetic material is exchanged between non-sister chromatids of homologous chromosomes, resulting in new combinations of alleles. In addition to crossing over, other processes such as independent assortment and random fertilization also contribute to genetic variation among offspring. Independent assortment during metaphase I of meiosis ensures different combinations of chromosomes in gametes, and fertilization combines alleles from two parents in new ways. Therefore, the correct answer is c) Through both crossing over and without crossing over.