The correct option is D 4
First we have to find the magic sum. From the diagonal, magic sum = 6 + 7 + 8 = 21
Now, from the first row, we get p + 3 + 8 = 21 So, p = 21 - 11 = 10
Now, from the second row, we get q + 7 + 9 = 21 So, q = 21 - 16 = 5
Now, from the third row we get 6 + r + 4 = 21 So, r = 21 - 10 = 11
Hence, p + q - r = 10 + 5 - 11 = 4