The long-term buildup of oxygen in earth’s atmosphere is a result of
a. volcanic outgassing
b. photosynthesis
c. limestone formation in the ocean
d. solar radiation splitting molecules of ozone in the stratosphere

B. Photosynthesis

Explanation:

Oxygen is necessary for the survival of most living species on Earth. But the atmosphere of the planet does not always contain this essential substance for life, and one of the greatest mysteries for science is to know how and when the photosynthesis of oxygen initially began, the process responsible for the production of oxygen from the rupture of water molecules on our planet. Now, a team led by geobiologists from the California Institute of Technology (Caltech) has found evidence of a precursor process in which manganese is involved, which acts as a predator of cyanobacteria, the first group of organisms that use photosynthesis to release oxygen in the environment.

Photosynthesis is the process by which the energy that comes from the Sun is used by plants and other organisms to break down water and carbon dioxide molecules to make carbohydrates and oxygen. Manganese is required for water breakdown to occur, so when scientists began to wonder what evolutionary steps had led to the presence of an oxygenated atmosphere on Earth, they began by paying attention to the evidence of the photosynthetic oxidation process of manganese in cyanobacteria, which was earlier in time. Since oxidation is simply a process that involves the transfer of electrons to increase the charge of an atom, and since this can be achieved using light or carbon dioxide, it could have occurred before the emergence of oxygen on our planet.

answer: the exterior temperature of commercial jet planes as they leave the stratosphere and return to the ground increases steadily.

explanation:

the lower most layer of atmosphere is troposphere which extends from 0 to 12 km above the surface of the earth. the temperature initially decreases as distance is increased from the earth's surface. commercial jets fly in lower part of the stratosphere. the stratosphere extends upto 50 km. the temperature in stratosphere starts rising again due to presence of ozone which traps the uv rays.

thus, when the planes leave the stratosphere and return to the ground, the exterior temperature increases steadily.

electromagnetic shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. shielding is typically applied to enclosures to isolate electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs. electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as rf shielding.

the shielding can reduce the coupling of radio waves, electromagnetic fields and electrostatic fields. a conductive enclosure used to block electrostatic fields is also known as a faraday cage. the amount of reduction depends very much upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in a shield to an incident electromagnetic

from wikipedia