+1 for
E.
(A) pronounced alterations in mood, which may be frequent and occasionally severe without
their constituting a clinical illness, from bipolar disorders
(B) bipolar disorders
and pronounced alterations in mood,
occurring frequently and occasionally severely, without constituting a clinical illness
(C) pronounced alterations in mood,
perhaps frequent and occasionally severe without constituting a clinical illness,
and bipolar disorders
(D)
between pronounced alterations in mood,
which may be frequent and occasionally severe without constituting a clinical illness,
from bipolar disorders -->
"Distinguish between X from Y" is unidiomatic (E)
between pronounced alterations in mood,
which may be frequent and occasionally severe without constituting a clinical illness,
and bipolar disorders -->
Correct, "Distinguish between X and Y" is correct idiom, and rectifies modifier errorHence,
E.
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The few, the fearless !Thanks 