What is the time ,space Complexity of the following code:

Question

int a=0, b=0;
for (i=0; i<N; i++){
a=a+rand();
}
for(j=0;<M;j++){
b=b+rand();
}

Options :
1. O(N*M)time, O(1)space
2. O(N+M)time,O(N+M)space
3. O(N+M)time,O(1)space
4. O(N*M)time,O(N+M)space

Answer
Option :
Explanation: