The binary search algorithm in the text makes recursive on subarrays of the array passed to the algorithm. The index values of the array the algorithm searches run from first to last. The subarrays are dermined using the mid-point. How is the mid point calculate?

a) mid = (first - last)/2;
b) mid = (first + last)/2;
c) mid = (first + last)%2;
d) mid = (first - last)%2;

b) mid = (first + last)/2;