Final answer:
The most abundant component of dry air is nitrogen, constituting about 78% of the Earth's atmosphere by volume. The correct option is 3.
Step-by-step explanation:
The most abundant component of dry air is nitrogen. When considering the composition of the Earth's atmosphere, nitrogen makes up approximately 78% of dry air by volume. Oxygen is the second most abundant at about 21%, followed by argon at around 1%, and then trace amounts of other gases such as carbon dioxide, which occupy much smaller fractions.
Argon is the most prevalent of the noble gases present in our atmosphere. Combined, these gas components, especially nitrogen and oxygen, play critical roles in supporting life on Earth and maintaining various biological and physical processes.