In the Featured Study Which Investigated the Impact of Combining

In the Featured Study which investigated the impact of combining insight therapy and medication, the researchers speculate that the combined treatment they tested may be best-suited for dealing with

A) both the biological and psychosocial substrates of old-age depression.
B) the biological substrate, but not the psychosocial substrate of old-age depression.
C) the psychosocial substrate, but not the biological substrate of old-age depression.
D) the genetic substrate, but not the biological substrate of old-age depression.