D Hits V Intending to Harm Her Mildly and Knocks

Multiple Choice

D hits V intending to harm her mildly and knocks her unconscious. Thinking that V is dead, D throws her into a river. V is still alive at that point but later drowns. D has committed the AR of manslaughter because:

A) The first act, an assault, was the act which killed.
B) The last act (ie: drowning) was accompanied by MR.
C) What occurred was really one series of acts or a continuing act.
D) Drowning was the medical cause of death.