Which letter above represents a 3λ difference in path length?

Please give me clarity about the question. I’m not able to figure out what the question means.

If you look clearly he path difference is zero in the centre. The variation of intensity will help direct you to find out the path difference. The intensity falls to zero as we move towards right or left and reches the minimum and then there is the region of minimum. After that there is agaion the region of high intensity and the distance between two peaks depicts the path difference of length. Hence with path difference being zero at the centre , the letter E position has a path difference of 3