Suppose that you are working with Drosophila and are studying genes, a, b, c, d, e, and f that are all linked in a region on a chromosome, but their order is unknown. In your work, you find that five deletions in the same region uncover recessive alleles of the genes as follows:
Deletion 1 uncovers a, b, and c.
Deletion 2 uncovers a and c.
Deletion 3 uncovers a, c, and e.
Deletion 4 uncovers c, d, and e.
Deletion 5 uncovers d, e, and f.

a. What is the order of the genes?

b. Suppose you systematically attempt to generate a chromosomal deletion (using X?rays) that lacks all five genes, but you are unsuccessful. Suggest a plausible explanation for this.