Infrared telescopes are usually placed on high-flying airplanes or on satellites in space

In order to improve visibility

Explanation:

Infrared telescopes are made using infrared cameras that contain infrared detectors which are solid-state and are maintained at very cold (cryogenic) temperatures

Infrared radiation is absorbed by water vapor which is present in the Earth's atmosphere, leading to the limitation of the use of infra red telescopes at high altitudes such as mountains, high flying planes or satellites

d

explanation:

i think the answer is d. but im not sure!

answer;

d. are made mostly of liquid

explanation;

-the general   composition and structure planets includes; they have a thick gas and liquid layer covering a small,solid core. mostly the gases are hydrogen and helium atmosphere and layers of liquid hydrogen. for instance neptune and uranus are examples of the outer planets, they have a core covered by ice and ammonia.

-neptune's atmosphere is hydrogen and helium with a bit of methane so there is no oxygen to breath and the interior is made up of frozen water and ammonia with a rock and iron core. thus, there is no liquid water or solid surface to survive.