Final answer:
A dependent task cannot be started until a previous task is completed. Such tasks are important in project scheduling to maintain the proper order and avoid delays. An example is not being able to install a roof before constructing walls. Option 3.
Step-by-step explanation:
A task that cannot be started until a previous task is completed is known as a dependent task. In project management, dependent tasks are those that rely on the completion of one or more tasks before they can be initiated.
These tasks are part of a sequence where the initiation of one task depends on the completion of its predecessor task, making it impossible for them to occur concurrently.
For example, in the construction of a house, the task of installing the roof (dependent task) cannot start until the walls are constructed (predecessor task).
Understanding and identifying dependent tasks is crucial for creating an effective project schedule and ensuring that tasks are completed in the correct order to avoid delays.
Hence, the right answer is option 3.