The answer is actually 1 & 17, maybe you meant to put 1&17 as option b
Answer:

Explanation:
We have to take into account the expression for the position of the fringes

where m is the number of the maximum, d is the separation of the slits, D is the distance to the screen.
(a) By replacing we obtain

(b) more information is required to solve this point. Please complete the information.
HOPE THIS HELPS!