Mr Lim Has Been Struggling with the Onset of Early

Mr. Lim has been struggling with the onset of early dementia. He is having a very hard time remembering his address, his grandchildren's names, and his daily routine. Mr. Lim was accepted into a clinical trial for a new drug to test its effectiveness compared with other medications on the market in slowing down the symptoms of dementia. Mr. Lim, without his knowledge, was placed in the placebo group and many of the other participants were randomly selected for placement in five different medication groups. Mr. Lim was initially assessed; he was given a sugar pill for the next 6 months with periodic neurocognitive assessments to monitor any change. Mr. Lim was part of what type of research design?

A) mixed factorial design
B) between-subjects design
C) within-subjects design
D) quasi-experimental design