Question

gold has been used in the field of medicine for over four thousand years. the ancient chinese used drugs containing gold to treat everything from smallpox and measles to joint and lung disease, apparently considering gold a sort of panacea. medical manuals in seventeenth - century europe suggested using gold for fevers, fainting, and melancholy. even during the 1920s, gold therapy was a popular treatment for tuberculosis. despite its popularity, however, the efficacy of medicinal gold was rarely supported by reliable scientific evidence. because medicines and medical practice were not always well regulated, early doctors were free to prescribe treatments—such as gold—without proof that they actually worked. modern research, however, indicates that gold does have some well - founded medical uses. for instance, gold salts have been shown to palliate the symptoms of rheumatoid arthritis. when patients receive regular injections of gold, it begins to accumulate in their muscles; this reduces joint inflammation, relieving pain and preventing further damage. researchers are also actively investigating the ability of gold nanoparticles to target cancer cells, which could help doctors identify the disease and deliver medication more efficiently. such findings confirm that gold is, as people have believed for thousands of years, rich in medical potential. what is the meaning of efficacy as used in the passage? effectiveness accessibility efficiency safety

Explanation:

The passage discusses that medicinal gold lacked reliable scientific proof that it "actually worked" when referring to its efficacy. Contextually, this refers to whether the treatment produces the intended healing effect, which matches "effectiveness". "Accessibility" refers to availability, "efficiency" relates to resource use, and "safety" refers to lack of harm, none of which fit the context.

Answer:

effectiveness