Answer:
Part a)
Width of the slit is

Part b)
Ratio of intensity is given as

Explanation:
Part a)
As we know by the formula of diffraction we will have

so we have


so we will have


Part b)
As we know that the intensity in diffraction pattern is given as


so for angle 45 degree



It is indirectly proportional or inverse so it would be C
There's no general rule.
Displacement is the length of a straight line from start to finish, and distance is how far you actually traveled from start to finish.
The only thing we really know is that distance can never be shorter than displacement. So I guess the answer is:
<em>The numerical ratio of displacement to distance is always 1 or less</em>.
(But it has to be written ALL IN CAPITALS.)