It would be 3 days because if there are 30 chickens at first and you can feed them for 4 days, then there must be 120 pieces of chicken food. If you have 40 chickens, then you have to divide 120 by 40 which gets you 3 days.
C . Ignore facts that contradict your position is your answer :)
D. You want it to be eye catching to the audience, but you also want it to be relevant to the subject you're talking about. A long title may bore the audience.
