The part of the small intestine most likely to develop an ulcer from exposure to gastric juice is the

duodenum

Explanation:

Ulcers most commonly occur in the first part of the small intestine below the stomach known as the duodenum.  Usually, the lining of the intestine keeps the intestine from being hurt by stomach acid and digestive juices. If this protective layer breaks down, stomach acids can damage the walls of the intestine and cause an ulcer. A main cause of an ulcer is a bacteria you may have called Helicobacter pylori (H-pylori).

the diploid number of chromosomes is sometimes represented by the symbol 2n. for the fruit fly, the diploid number is 8, which can be written as 2n = 8, where n represents twice the number of chromosomes in a sperm or egg cell.

i believe it would cause an increase of percipitation, though i could be wrong. so i would say b is the answer.