Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks.

Through the centuries, the dream of medieval alchemists was to discover how to turn lead and ___(1)___ "base" metals into gold. Some were fakes, but many were learned men with philosophical goals. Their ___(2)___ was based on the ancient idea that all matter consists of different proportions of just four substances - earth, water, fire, and air. They believed that it was possible to adjust the proportions of the elements that made up lead by chemical means so that it turned into gold, a process called transmutation. Their experiments were concerned with finding the substance - ___(3)___ they called the philosopher's stone - that, when added to lead, would cause this astonishing change to take place. Alchemists also searched for the elixir of life, a substance that could cure diseases and ___(4)___ life. They failed on both counts. ___(5)___, their techniques for preparing and studying chemicals helped lay the foundation for the modern science of chemistry.
(Adapted from “VSTEP Collection”)