SAT English Practice Question

Many scientific discoveries have been made by accident—while scientists were studying one thing, they stumbled upon something else entirely. One such example involves the discovery of penicillin, a powerful antibiotic that revolutionized medicine, by Alexander Fleming. While studying bacteria in 1928, Fleming left a petri dish of bacteria uncovered in a lab. When he returned, Fleming observed that a mold had grown in the dish, and that, surprisingly, the bacteria surrounding the mold had died. The discovery of penicillin provides a powerful illustration of how ______.

1. A.an unexpected discovery can be the result of scientific inquiry.
2. B.scientific discoveries are often made in controlled laboratory settings.
3. C.researchers must carefully control their experiments to ensure accurate results.
4. D.the scientific method is the only reliable way to make new discoveries.