Read the following passage and mark the letter A, B,C or D to indicate the correct answer to each of the questions.

From the start of his career as a writer, Mark Twain was fascinated with inventions. As a result, he chose to spend much of his available income on various types of inventions, generally without much success. In fact, he lost most of the money he invested. By 1887, the 49-year-old author had invested most of his money in one project, the Paige typesetting machine.

Twain expected the Paige machine to be completed in 1889. Unfortunately, the machine was never completely finished, and by the early 1890s, Twain knew he was in a serious financial situation. He worked hard to take care of his problems by producing a number of books in a row. He wrote A Connecticut Yankee in King Arthur’s Court (1892), An American Claimant (1892), Tom Sawyer Abroad (1893), and Pudd’nhead Wilson (1894). However, all of these works did not solve his financial problems, and he was forced to declare bankruptcy

This passage mainly discusses how an author _________.