I'm pretty sure it's railroads, because there's not that many highways in Siberia, the rivers would be frozen over, and there's not a ton of people in Siberia. I'm sorry if I'm wrong.
The correct answer is - d. deciduous forest.
The giant panda lives in the deciduous forested parts of China were the climate is temperate, wet, moisty, and most importantly covered in bamboo trees. The bamboo tree is the only food source of the giant pandas, and it is essential for their survival. Unlike the other bears the giant panda is not an omnivore, and in its evolution due to a genetic mutation it lost its taste for meat and became exclusively a bamboo eater. It is on the verge of extinction nowadays and strict measures are needed for this lovely animal to be protected and preserved.
Answer: As altitude increases, atmospheric pressure decreases
Explanation:
Atmospheric pressure
is defined as the force
per unit area
the air that forms the atmosphere exerts on the Earth's surface:

It should be noted that as the altitude increases less air is above and, therefore the air weights less. This is because the atmosphere losses density as we ascend, causing less air.
However, it is important to point out this decrease in pressure is not linear, since at the beginning (in the first kilometers above sea level) it reduces more rapidly than in the next kilometers above. That is why this relationship between atmospheric pressure and altitude is exponential.