@vijay_jr i will try to put a different perspective here:
let us assume there are 4 jobs:1,2,3,4 and 2 persons:p,q.
l.h.s of option c says, every job is completed by either p or q.
Here the aim is every job getting completed irrespective of who did it.
This becomes true even when a job can't be done by p but can be done by q.
r.h.s says, every job is completed by p or every job is completed by q.
This becomes true only when either p can do all jobs or q can do all jobs.
i will give a example : p can do jobs 1,2 and q can do jobs 3,4. Now l.h.s becomes true here.( because all jobs 1,2,3,4 are getting completed)and r.h.s becomes false( since neither p can do all jobs nor q can do all jobs).
since true-> false is false, option c is false.
or you can refer this answer