A、Windows operating system B、a graphical user interface C、the use of icons D、the use of personal computer B

One of the most powerful tools ever developed is the P. C., the personal computer. One of the companies important to the history of the P. C. is Apple Computer. Apple is based in Cupertino, California.
  Steve Wozniak and Steve Jobs started the company in 1976. Mister Wozniak designed an early personal computer, the Apple One. At that time, people who wanted to work with computers often built their own, or used larger systems.
  Early personal computers had limited uses. Users had to write commands. This was true of the Apple One. But other Apple computers operated with a system known as a graphical user interface. Users chose from little pictures called icons. Researchers at Xerox designed such a system. But Apple was the first to make it popular. Today most personal computers use icons.
  Steve Wozniak and Steve Jobs tried to sell their ideas to other companies. They were rejected. But soon they found investors. Apple began to sell shares to the public in 1980. The company became worth more than one-thousand-million dollars.
  In 1981, International Business Machines began to sell a personal computer that many people bought. I. B. M. was the biggest computer company in the world. But Apple was known for its creativity. In 1984, it released the first Macintosh. These computers were simple to use.
  Over the years, Apple gained a following of loyal users. But then lower-priced computers appeared. These used the Windows operating system made by Microsoft. Most personal computers today use Windows.