Final answer:
A group of closely related tasks in a project is known as a phase, which includes various activities and leads to milestones or deliverables.
Step-by-step explanation:
A group of closely related tasks that encompass a major section of your project is known as a phase. A phase represents a significant segment within a project, characterized by the completion of a set of related activities or tasks that are crucial to achieving an overall goal. The term 'milestone' typically refers to a specific, measurable achievement that signifies the completion of a key stage in a project. 'Activity' can be a part of a phase and is usually made up of smaller, detailed tasks. Whereas a 'deliverable' is the final output or product that is delivered to a client or stakeholder.