Reading africa's big break
1. which of the following best describes the purpose of the article?
a. the passage is an advertisement to encourage you to buy something.
b. the passage is to persuade you to make a certain decision.
c. the passage is to inform the reader of opportunities to take part in a gathering.
d. the passage is to inform the reader of discoveries in the field of geology.

Explanation:

the passage is to inform the reader to opportunity to take part in the gathering

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.