Which of the following best completes the passage below?
Established companies concentrate on defending what they already have. Consequently, they tend not to be innovative themselves and tend to underestimate the effects of the innovations of others. The clearest example of this defensive strategy is the fact that___.

A. ballpoint pens and soft-tip markers have eliminated the traditional market for fountain pens, clearing the way for the marketing of fountain pens as luxury or prestige items
B. a highly successful automobile was introduced by the same company that had earlier introduced a model
that had been a dismal failure
C. a once-successful manufacturer of slide rules reacted to the introduction of electronic calculators by trying to make better slide rules
D. one of the first models of modern accounting machines, designed for use in the banking industry, was purchased by a public library as well as by banks
E. the inventor of a commonly used anesthetic did not intend the product to be used by dentists, who currently account for almost the entire market for that drug.