A student conducted a sequence of two-point crosses for four genes, specifically, genes a, b, c, and d. These genes have the following recombination frequencies:

a and b = 50%
a and c = 50%
a and d = 50%
b and c = 20%
b and d = 9%
a and d = 29%

Considering the given data, which of the following statements is true?

• A. Gene b is located on a different chromosome from genes a, c, and d.
• B. All genes are located on the same chromosome.
• C. Genes c and d are on separate chromosomes from genes a and b.
• D. Gene a is located on a different chromosome than the other genes.