If two genes are on the same chromosome and rarely assort independently,
a. crossing-over never occurs between the genes
b. crossing-over always occurs between the genes
c. the genes are probably located far apart from each other
d. the genes are probably located close to each other

the genes are probably located close to each other.

Explanation:

If two genes are on the same chromosome and rarely assort independently,the genes are probably located close to each other. Mendel's law of independent assortment states that the alleles of two different genes get sorted into gametes independently of one another. The allele a gamete receives for one gene does not influence the allele received for another gene.

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