The path difference at point A due to light from source at $S_1 $ and $S_2$ is
$ S_2 A -S_2 A =S_2 -S_1 $
Since A is a bright point $|S_2 -S_1| $ must be an integral multiple of $\lambda$
At B also the path difference is $S_1 B -S_2 B =|S_1 -S_2| $
Which is an integral multiple of X
$\therefore$ B is also a bright point .
Hence d is the correct answer.