Although Gold Salts Have Been Utilized for the Treatment of Inflammation

Although gold salts have been utilized for the treatment of inflammation for more than 65 years,why are they currently agents of last resort-reserved for those patients who do not respond to anything else?

A) Gold salts are slow acting.
B) Gold salts are less toxic than DMARDs.
C) Gold salts are an older and less expensive drug.
D) Gold salts require regular urine protein monitoring.