In the shown project network (Activity-on-Arrow), the excavation activity starts at Event 1 and finishes at Event 2 (the arrow's tail and head).

Introduction / Context:
Network diagrams in project management (particularly Activity-on-Arrow, AOA) depict activities as arrows connecting two events (nodes). This question checks whether you can read the basic meaning of an activity arrow independent of its description or duration annotation.

Given Data / Assumptions:

• An excavation activity is shown as an arrow between Event 1 and Event 2.
• No unique task subtype (e.g., footing) is explicitly labeled.
• Any numeric duration (e.g., 8 units) would be secondary to the definition.

Concept / Approach:
In AOA, the tail node indicates the start event, the head node indicates the finish event. The arrow itself is the activity. A label (if provided) names the activity; a duration (if provided) quantifies its time requirement. The fundamental interpretation is the logical sequence from start event to finish event.

Step-by-Step Solution:
1) Identify the notation: arrow between Event 1 → Event 2.2) Interpret semantics: tail = start event, head = finish event.3) Recognize that specific sub-scope (e.g., footing) is not implied unless labeled explicitly.4) Conclude that the correct meaning is: the excavation starts at Event 1 and ends at Event 2.

Verification / Alternative check:
Standard AOA conventions in CPM literature define activities strictly as arrows joining two events that mark commencement and completion of that activity.

Why Other Options Are Wrong:

• Activity of excavation of a footing: Overly specific; not stated by the network label.
• Activity of excavation which takes 8 units of time: Duration may exist but is not the primary definition.
• None of these: Incorrect because the AOA meaning matches option B exactly.

Common Pitfalls:

• Confusing a descriptive task type (footing) with a generic excavation activity.
• Overemphasizing duration annotations instead of the logical start–finish definition.

Final Answer:
Activity of an excavation which starts at Event 1 and ends at Event 2.