The answer is 2-to-the-power-of-n, since for every input, the number of different combinations doubles. From your list I think answer A is meant to indicate 2ⁿ.
// making the class
class Counter {
int counter;
int limit;
// Constructor
Counter(int a, int b){
counter = a;
limit = b;
}
// static function to increment
static increment(){
if(counter<limit)
nCounter+=1;
}
// Decrement function
void decrement(){
if(counter>0)
nCounter-=1;
}
int getValue(){
return counter;
}
static int nCounter;
int getNCounters(){
return nCounter;
}
};
// Initializa the static
int Counter::nCounter = 0;
