Question

passage
american copyright laws, laws that prohibit the use, distribution, or adaptation of another’s product without permission, first applied only to the copying of books, but now cover such diverse products as sound recordings, motion pictures, and computer programs. the federal copyright act of 1790 allowed copyright protection for 14 years with one 14 - year extension allowed (if the author survived the first 14 - year term). the copyright act of 1909 extended copyright protection to 28 years with a 28 - year renewal, and the copyright act of 1976 extended it further, to 75 years.

question
what is the main purpose of this passage?
○ to explain the need for copyright laws
○ to show how copyright laws have been applied
○ to indicate how copyright laws have changed

Explanation:

The passage first introduces what American copyright laws are, then describes their evolution: initially applied to books, now covering more products, and details changes in copyright protection duration via different acts (1790, 1909, 1976). The first option is incorrect as the passage doesn't explain the need for copyright laws. The second option is wrong because it's not about how the laws are applied but how they've changed over time. The third option matches as the passage shows the changes in copyright laws (scope of products, protection duration).

Answer:

To indicate how copyright laws have changed