Earliest finish of an activity is always A. Greater than earliest event time of the following node B. Less than earliest event time of the following node C. Less than or equal to earliest event time of the following node D. Greater than or equal to earliest event time of the following node

The correct answer is: D. Greater than or equal to earliest event time of the following node.

The earliest finish time of an activity is the earliest time that the activity can be completed, given the start and finish times of the activities that precede it. The earliest event time of a node is the earliest time that the node can be reached, given the start and finish times of the activities that lead into it.

Since the earliest finish time of an activity must be greater than or equal to the earliest event time of the node that it leads into, the answer is D.

Here is a more detailed explanation of each option:

• Option A: Earliest finish of an activity is always greater than earliest event time of the following node. This is not always true. For example, if an activity has no predecessors, then its earliest finish time will be equal to its earliest event time.
• Option B: Earliest finish of an activity is always less than earliest event time of the following node. This is also not always true. For example, if an activity has a predecessor that has a late finish time, then the earliest finish time of the activity will be greater than the earliest event time of the following node.
• Option C: Earliest finish of an activity is always less than or equal to earliest event time of the following node. This is true. The earliest finish time of an activity must be greater than or equal to the earliest event time of the node that it leads into.
• Option D: Earliest finish of an activity is always greater than or equal to earliest event time of the following node. This is also true. The earliest finish time of an activity must be greater than or equal to the earliest event time of the node that it leads into.