A. The pressure is lower as you gain altitude because there are more molecules of oxygen and nitrogen. B. The pressure is lower as you gain altitude because there are less molecules of oxygen and nitrogen. C. The pressure is the same because there is no change in the number of molecules.
The price of a cockatiel depends on a few factors. Firstly the price depends on whether or not the bird is tamed. For a tamed cockatiel it would cost around $80 - $120 and a untamed cockatiel would cost $15-$30 (AUS) Also the colouring of the cockatiel plays a part in the cost of the bird, as more rare colours (such as lutino or pearl cinnamon) may increase the cost of the cockatiel.
The cost of a ringneck will often depend upon the age of the bird, the breeder selling it, the species of parrot, colors and the geographical location. On average, the cost of this type of parrot can range anywhere from $100 to as much as $1,200 for a rarer species or color. A common bird such as those green and blue in color can be within the $250 to $450 range, while the grays and turquoise birds can cost as much as $600 to $1,000. A rarer ringneck such as the violets and cleartails can cost more than $1,000 each.