Question 3209 Deck General

The correct answer is D) 21 percent. The percentage of oxygen in a typical sample of uncontaminated air is approximately 21 percent. This is a well-established fact based on the composition of the Earth's atmosphere, which is primarily made up of nitrogen (78%) and oxygen (21%), with small amounts of other gases. This standard atmospheric composition is widely recognized and referenced in various regulations and guidelines, including those related to the US Coast Guard Captain's License Examinations. The other options, A) 12 percent, B) 15 percent, and C) 18 percent, are incorrect as they do not accurately reflect the actual oxygen content in uncontaminated air.