The demonstrates how long a part may survive or the maximum allowable loads that can be applied without causing failure. a. fatigue limit
b. endurance test
c. fatigue test
d. endurance limit

c. Fatigue test

Explanation:

In material science and in creation of an object that would carry load, the object is subjected a load testing known as fatigue testing, this is required to determine the capability of the equipment and the extent to which it can sustain it's maximum load without failure, this is known as fatigue testing. This is required to guard against many failures of equipments.

i believe the answer is: returns on investments, no wages

people who belong in upper class society would most likely get there by obtaining multiple source of income, which a certain percentage of ownership for businesses. since most of them are job creator, they would most likely get their money from profit, not wages.