About Question enthuware.ocajp.i.v8.2.1257 :

[alkour]

Option C.
Not clear: "An empty switch block is a valid construct".
Does it make sense?

I tried to compile.
switch () {
case 'a' :
}

It illegal expression. So it can not be true.

[admin]

It says empty switch block. Not empty switch condition.
switch(variable){
}

[alkour]

Thank you.