CSF’s are factors that are needed for the business to be successful (and come from the mission statement). Improving market share is a CSF.
Objectives are more specific targets that will be set that help to achieve the CSF’s., so 3 is more likely to be an objective.
However, it does depends on the nature of the business (for example, I do not know what farmers have to do with anything given that you have written nothing about the nature of the business).
Why are you attempting a question for which you do not have an answer? You should be using a Revision Kit from one of the ACCA Approved Publishers – they have answers and explanations.