Answer
a) 90720
b)50400
c)80640
Work Step by Step
a) First we select 6 people such that bride is always in the picture = 1$\times$9$\times$8$\times$$\times$7$\times$6$\times$5=15120
Number of arrangements of bride = 6
Total arrangements = 6$\times$15120 = 90720
b) Again we pick 6 people such that bride and groom are always in the picture = 1$\times$1$\times$8$\times$7$\times$6$\times$5=1680.
Ways to arrange bride and groom = 6P4 = 6$\times$5 = 30
Total arrangements = 30$\times$1680 = 50400.
c) Number of ways in which either bride or groom is in picture = (Arrangements when bride is in picture - arrangement when both bride and groom in picture) + (Arrangements when groom is in picture - arrangement when both bride and groom in picture) i.e.
(90720 - 50400) + (90720 - 50400) = 80640.
