What number will the following code display on the computer screen? 

int sum = 0; 

int y = 0; 

do 

{ 

for (int x = 1; x <= 5; x += 1) 

sum += x; 

//end for 

y += 1; 

} while (y < 2); 

cout << sum << endl; 

a. 5 

b. 8 

c. 15 

d. 30