Which of the following is a test-first approach, where tests that express a shared understanding...

This answer is correct because Behavior-Driven Development (BDD) is a test-first approach, where tests that express a shared understanding from stakeholders of how the application is expected to work, are first written in business-readable language (following the Given/When/Then format), and then made executable to drive development. BDD is a collaborative approach that involves testers, developers, business analysts, product owners, and other stakeholders in defining the expected behavior of the application using scenarios that describe the preconditions, actions, and outcomes of the application. BDD scenarios are written using a domain-specific language (DSL) that can be translated into executable test cases using tools such as Cucumber or SpecFlow. BDD aims to improve communication, collaboration, and feedback among the team members, and to deliver software that meets the customer’s needs and expectations. References: ISTQB Glossary of Testing Terms v4.0, ISTQB Foundation Level Syllabus v4.0, Section 3.1.1.4

, Requirements Engineering Fundamentals.