Being a business analyst What is the biggest task you may think in gathering requirements?

As part of the requirement gathering the biggest task is requirements elicitation. Requirement elicitation is much more than requirement gathering from different stakeholders. If the stakeholder has clear requirements then gathering that information is much easier. But most of the time the stakeholder might have wants and needs but may not be able clearly express them. They might know there is a problem but may not know the exact problem.

Part of the BA's job is to define the problem and determine what should be done to address it. The elicitation process helps facilitate this work.