In a network flow diagram, two jobs 'a(i, k)' and 'b(j, k)' of durations '4' and '5' days repectively, enter an event 'k' then which of the following will be earliest start day of 'k' provided that (i, k) and (j, k) have started earlier at 3rd and 4th day respectively?
- 7th
- 8th
- 9th
- 6th