Final answer:
True statements about genes include that linked genes are located on the same chromosome and that alleles of genes on the same chromosome may assort independently if they are separated by crossing-over during meiosis.
Step-by-step explanation:
The correct statements about genes are linked genes are located on the same chromosome and alleles of genes on the same chromosome can sometimes assort independently due to recombination. Therefore, from the options given, the true statements are 'Linked genes are located on the same chromosome' and 'Alleles of genes on the same chromosome always fail to assort independently' is not always true because crossing-over during meiosis can allow them to assort independently if they are far enough apart.
Genes that are on nonhomologous chromosomes will always sort independently during meiosis, but genes on the same chromosome can also sometimes sort independently due to the random event of recombination. This infers that alleles of genes that are located far apart on the same chromosome can indeed assort independently. Therefore, the accurate statements are 'c' and partially 'b' under certain conditions, but 'a' is incorrect because alleles of genes located on the same chromosome may not always assort independently, especially if they are closely linked.