People in this country annually spend more than a billion dollars a year on prescription drugs, and for most patients the medicines have only marginal effects, if any, on symptoms and does nothing to stop the underlying disease process that eats away at the brain

A. annually spend more than a billion dollars a year on prescription drugs, and for most patients the medicines have only marginal effects, if any, on symptoms and does nothing
B. spend more than a billion dollars a year on prescription drugs, but for most patients the medicines have only marginal effects, if any, on symptoms and do nothing
C. annually spend more than a billion dollars a year on prescription drugs, but for most patients the medicines are having only marginal effects, if any, on symptoms and do nothing
D. annually spend more than a billion dollars on prescription drugs, but for most patients the medicines has only marginal effects, if any, on symptoms and are doing nothing
E. are spending greater than a billion dollars a year on prescription drugs, and for most patients the medicines have only marginal effects, if any, in symptoms and do nothing

OA is B
I would Love an expert to analyse a best approach in dealing with this.