[R] LMER: How to specify Random Effects

[Ubuntu Diego]

I saw different specifications for Random Effects and I'm confused about 
the use of "/" and  the use of "(0+...|)" .
Let say we have a nested structure where some countries have some 
several plants in different states and we measure the reaction to a drug.

The list of Countries = USA, France, Italy
The States for USA = Michigan, Florida, California
The States for France =  Paris, Orleans
The States for Italy =  Venezia, Sienna, Florence, Rome, Napoli , Sicilia

Plants were classified as High and Low

is this the way to specify a possible model ?

lmer(Reaction ~ Drug + (1| Country / State / Plant) , data)

or should I use something like this
A) lmer(Reaction ~ Drug + (0| Country / State / Plant) , data)
B) lmer(Reaction ~ Drug + (1| Country ) + (0+Country | State / Plant) , 
data)
C) lmer(Reaction ~ Drug + (1| Country ) + (0+Country | State / Plant) + 
(0+Country + State | Plant), data)
D) lmer(Reaction ~ Drug + (1| Country ) + (0+Country | State ) + 
(0+Country + State | Plant), data)

Thanks