A requirement is a statement about an intended productthat specifies what it should do or how it should perform.

The following are Data Gathering Techniques except - 

The method aims to obtain data from a purposely selected group of individuals rather than from a statistically representative sample of a broader population.

If the researcher's goal is to explore some issues, what is the best data gathering technique?

If the researcher's goal is to answer specific questions, what is the best data gathering technique?

A special kind of scenario that breaks down system requirements into user functions

Functional requirements define the system’s quality characteristics.

The purpose of requirements gathering is to describe what the proposed system should do, but NOT how it should do it or what it should look like.